Cross reality system with wifi/gps based map merge

ABSTRACT

A portable electronic system receives a set of one or more canonical maps and determines the sparse map based at least in part upon one or more anchors pertaining to the physical environment. The sparse map is localized to at least one canonical map in the set of one or more canonical maps, and a new canonical map is created at least by merging sparse map data of the sparse map into the at least one canonical map. The set of one or more canonical maps may be determined from a universe of canonical maps comprising a plurality of canonical maps by applying a hierarchical filtering scheme to the universe. The sparse map may be localized to the at least one canonical map at least by splitting the sparse map into a plurality of connected components and by one or more merger operations.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of pending U.S. patentapplication Ser. No. 17/180,453 filed on Feb. 19, 2021 entitled “CROSSREALITY SYSTEM WITH WIFI/GPS BASED MAP MERGE,” which claims priority toU.S. Provisional Patent Application Ser. No. 62/979,362 filed Feb. 20,2020 entitled “CROSS REALITY SYSTEM WITH WIFI/GPS BASED MAP MERGE.” Thepresent application is related to U.S. patent application Ser. No.17/185,558 filed on Feb. 25, 2021 entitled “CROSS REALITY SYSTEM FORLARGE SCALE ENVIRONMENT RECONSTRUCTION,” under Attorney Docket No.ML-1023US and is also related to U.S. patent application Ser. No.17/185,706 filed Feb. 25, 2021 entitled “CROSS REALITY SYSTEM WITHBUFFERING FOR LOCALIZATION ACCURACY,” under Attorney Docket No.ML-1017US. The contents of the aforementioned patent applications arehereby expressly incorporated by reference in their entirety for allpurposes.

TECHNICAL FIELD

This application relates generally to a cross reality system.

BACKGROUND

Computers may control human user interfaces to create an X reality (XRor cross reality) environment in which some or all of the XRenvironment, as perceived by the user, is generated by the computer.These XR environments may be virtual reality (VR), augmented reality(AR), and mixed reality (MR) environments, in which some or all of an XRenvironment may be generated by computers using, in part, data thatdescribes the environment. This data may describe, for example, virtualobjects that may be rendered in a way that users' sense or perceive as apart of a physical world and can interact with the virtual objects. Theuser may experience these virtual objects as a result of the data beingrendered and presented through a user interface device, such as, forexample, a head-mounted display device. The data may be displayed to theuser to see, or may control audio that is played for the user to hear,or may control a tactile (or haptic) interface, enabling the user toexperience touch sensations that the user senses or perceives as feelingthe virtual object.

XR systems may be useful for many applications, spanning the fields ofscientific visualization, medical training, engineering design andprototyping, tele-manipulation and tele-presence, and personalentertainment. AR and MR, in contrast to VR, include one or more virtualobjects in relation to real objects of the physical world. Theexperience of virtual objects interacting with real objects greatlyenhances the user's enjoyment in using the XR system, and also opens thedoor for a variety of applications that present realistic and readilyunderstandable information about how the physical world might bealtered.

To realistically render virtual content, an XR system may build arepresentation of the physical world around a user of the system. Thisrepresentation, for example, may be constructed by processing imagesacquired with sensors on a wearable device that forms a part of the XRsystem. In such a system, a user might perform an initialization routineby looking around a room or other physical environment in which the userintends to use the XR system until the system acquires sufficientinformation to construct a representation of that environment. As thesystem operates and the user moves around the environment or to otherenvironments, the sensors on the wearable devices might acquireadditional information to expand or update the representation of thephysical world.

SUMMARY

Some aspects of the present application relate to methods and apparatusfor providing extended reality (cross reality or XR) scenes. Techniquesas described herein may be used together, separately, or in any suitablecombination.

Further aspects of the present application relate to a computing deviceconfigured for use in a cross reality system in which a portable deviceoperating in a three-dimensional (3D) environment renders virtualcontent. The computing device comprises at least one processor; acomputer-readable medium connected to the at least one processor, thecomputer-readable medium having stored therein information representinga canonical map; computer-executable instructions configured to, whenexecuted by the at least one processor, perform a method. The methodcomprises receiving, from the portable device, information representinga tracking map generated by the portable device and location metadataassociated with at least a portion of the tracking map; selecting asub-portion of the canonical map based at least in part on acorrespondence between the location metadata associated with at least aportion of the tracking map and location metadata associated with theselected sub-portion of the canonical map; merging the selectedsub-portion of the canonical map with the tracking map to obtain amerged map; and integrating the merged map with the canonical map.

In some embodiments, merging the selected sub-portion of the canonicalmap with the tracking map comprises: identifying a first plurality offeatures in the at least a portion of the tracking map; identifying asecond plurality of features in the selected sub-portion of thecanonical map; and identifying a transformation that aligns the firstplurality of features with the second plurality of features.

In some embodiments, merging the selected sub-portion of the canonicalmap with the tracking map further comprises computing the identifiedtransformation to align the first plurality of features with the secondplurality of features.

In some embodiments, integrating the merged map with the canonical mapcomprises replacing the selected sub-portion of the canonical map withthe merged map.

In some embodiments, integrating the merged map with the canonical mapcomprises extending the selected sub-portion of the canonical map basedon the merged map.

In some embodiments, receiving, from the portable device, the locationmetadata associated with at least a portion of the tracking mapcomprises receiving, from the portable device, global positioning system(GPS) location information indicative of a prior location of theportable device within the 3D environment.

In some embodiments, receiving the location metadata associated with atleast a portion of the tracking map comprises receiving locationmetadata associated with a tile of the tracking map.

In some embodiments, receiving the location metadata associated with atleast a portion of the tracking map comprises receiving locationmetadata associated with a persistent pose of the tracking map.

In some embodiments, receiving, from the portable device, the locationmetadata associated with at least a portion of the tracking mapcomprises receiving, from the portable device, wireless locationinformation indicative of a prior location of the portable device withrespect to a plurality of wireless network access points.

In some embodiments, the method further comprises storing the integratedcanonical map in the computer-readable medium.

In some embodiments, the portable device is a first portable device, andthe method further comprises localizing a second portable device basedon the integrated map.

Further aspects of the present application relate to a portablecomputing device configured for use in a cross reality system in which aplurality of portable devices operating in a three-dimensional (3D)environment render virtual content. The computing device comprises atleast one image sensor; at least one processor; computer-executableinstructions configured to, when executed by the at least one processor,perform a method. The method comprises constructing a tracking mapgenerated by the first portable device; associating location metadatawith a plurality of locations of the tracking map; sending to anetworked service the tracking map and associated location metadata foruse in a map merge process.

In some embodiments, the tracking map comprises a plurality ofpersistent poses; and associating location metadata with locations ofthe tracking map comprises associating location metadata with persistentposes of the plurality of persistent poses.

In some embodiments, the tracking map comprises a plurality of tiles;and associating location metadata with locations of the tracking mapcomprises associating location metadata with tiles of the plurality oftiles.

In some embodiments, the location metadata comprises first type locationmetadata associated with a first portion of the plurality of locationsof the tracking map and second type metadata associated with a secondportion of the plurality of locations of the tracking map; and the firsttype location metadata comprises wireless location metadata indicativeof a prior location of the first portable device with respect to aplurality of wireless network access points; and the second typelocation metadata comprises geo-location metadata indicative of a priorGPS location of the second portable device.

In some embodiments, the computer-executable instructions are furtherconfigured to convert wireless location metadata to geo-locationmetadata; and associating location metadata with the plurality oflocations of the tracking map comprises associating the geo-locationmetadata with at least one of the plurality of locations.

In some embodiments, converting wireless location metadata togeo-location metadata comprises calling a publicly-accessibleapplication programing interface (API).

Further aspects of the present application relate to a computing deviceconfigured for use in a cross reality system in which a portable deviceoperating in a three-dimensional (3D) environment renders virtualcontent. The computing device comprises at least one processor; acomputer-readable medium connected to the at least one processor, thecomputer-readable medium having stored therein information representinga canonical map and location metadata associated with the canonical map;computer-executable instructions configured to, when executed by the atleast one processor, perform a method. The method comprises receiving,from the portable device, information representing a tracking mapgenerated by the portable device and location metadata associated withat least a portion of the tracking map; determining, based on thelocation metadata associated with at least a portion of the tracking mapand the location metadata associated with the canonical map, whetherthere is at least one candidate sub-portion the canonical map thatlikely represents the same region of the 3D environment as a portion ofthe tracking map and; if it is determined that there is at least onecandidate sub-portion, performing merge processing comprising a featurebased comparison of the portion of the tracking map and the candidatesub-portion; and if it is determined that there are no candidatesub-portion, skipping the feature based comparison.

In some embodiments, the merge processing comprises: identifying a firstset of features in the at least the portion of the tracking map;identifying a second set of features in the candidate sub-portion of thecanonical map; and searching for a transformation that aligns the firstset of features with the second set of features with an error below athreshold.

In some embodiments, the merge processing further comprises: based onidentifying the transformation as a result of the searching,transforming the tracking map based on the identified transformation formerging with the candidate sub-portion.

In some embodiments, receiving, from the portable device, the locationmetadata associated with at least a portion of the tracking mapcomprises: receiving, from the portable device, global positioningsystem (GPS) location information indicative of a prior location of theportable device within the 3D environment.

In some embodiments, receiving the location metadata associated with atleast a portion of the tracking map comprises: receiving locationmetadata associated with a tile of the tracking map.

In some embodiments, receiving the location metadata associated with atleast a portion of the tracking map comprises: receiving locationmetadata associated with a persistent pose of the tracking map.

In some embodiments, receiving, from the portable device, the locationmetadata associated with at least a portion of the tracking mapcomprises receiving, from the portable device, wireless locationinformation indicative of a prior location of the portable device withrespect to a plurality of wireless network access points.

The foregoing summary is provided by way of illustration and is notintended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various FIGS. is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a sketch illustrating an example of a simplified augmentedreality (AR) scene, according to some embodiments;

FIG. 2 is a sketch of an exemplary simplified AR scene, showingexemplary use cases of an XR system, according to some embodiments;

FIG. 3 is a schematic diagram illustrating data flow for a single userin an AR system configured to provide an experience to the user of ARcontent interacting with a physical world, according to someembodiments;

FIG. 4 is a schematic diagram illustrating an exemplary AR displaysystem, displaying virtual content for a single user, according to someembodiments;

FIG. 5A is a schematic diagram illustrating a user wearing an AR displaysystem rendering AR content as the user moves through a physical worldenvironment, according to some embodiments;

FIG. 5B is a schematic diagram illustrating a viewing optics assemblyand attendant components, according to some embodiments.

FIG. 6A is a schematic diagram illustrating an AR system using a worldreconstruction system, according to some embodiments;

FIG. 6B is a schematic diagram illustrating components of an AR systemthat maintain a model of a passable world, according to someembodiments.

FIG. 7 is a schematic illustration of a tracking map formed by a devicetraversing a path through a physical world.

FIG. 8 is a schematic diagram illustrating a user of a cross reality(XR) system, perceiving virtual content, according to some embodiments;

FIG. 9 is a block diagram of components of a first XR device of the XRsystem of FIG. 8 that transform between coordinate systems, according tosome embodiments;

FIG. 10 is a schematic diagram illustrating an exemplary transformationof origin coordinate frames into destination coordinate frames in orderto correctly render local XR content, according to some embodiments;

FIG. 11 is a top plan view illustrating pupil-based coordinate frames,according to some embodiments;

FIG. 12 is a top plan view illustrating a camera coordinate frame thatincludes all pupil positions, according to some embodiments;

FIG. 13 is a schematic diagram of the display system of FIG. 9 ,according to some embodiments;

FIG. 14 is a block diagram illustrating the creation of a persistentcoordinate frame (PCF) and the attachment of XR content to the PCF,according to some embodiments;

FIG. 15 is a flow chart illustrating a method of establishing and usinga PCF, according to some embodiments;

FIG. 16 is a block diagram of the XR system of FIG. 8 , including asecond XR device, according to some embodiments;

FIG. 17 is a schematic diagram illustrating a room and key frames thatare established for various areas in the room, according to someembodiments;

FIG. 18 is a schematic diagram illustrating the establishment ofpersistent poses based on the key frames, according to some embodiments;

FIG. 19 is a schematic diagram illustrating the establishment of apersistent coordinate frame (PCF) based on the persistent poses,according to some embodiments;

FIGS. 20A to 20C are schematic diagrams illustrating an example ofcreating PCFs, according to some embodiments;

FIG. 21 is a block diagram illustrating a system for generating globaldescriptors for individual images and/or maps, according to someembodiments;

FIG. 22 is a flow chart illustrating a method of computing an imagedescriptor, according to some embodiments;

FIG. 23 is a flow chart illustrating a method of localization usingimage descriptors, according to some embodiments;

FIG. 24 is a flow chart illustrating a method of training a neuralnetwork, according to some embodiments;

FIG. 25 is a block diagram illustrating a method of training a neuralnetwork, according to some embodiments;

FIG. 26 is a schematic diagram illustrating an AR system configured torank and merge a plurality of environment maps, according to someembodiments;

FIG. 27 is a simplified block diagram illustrating a plurality ofcanonical maps stored on a remote storage medium, according to someembodiments;

FIG. 28 is a schematic diagram illustrating a method of selectingcanonical maps to, for example, localize a new tracking map in one ormore canonical maps and/or obtain PCFs from the canonical maps,according to some embodiments;

FIG. 29 is flow chart illustrating a method of selecting a plurality ofranked environment maps, according to some embodiments;

FIG. 30 is a schematic diagram illustrating an exemplary map rankportion of the AR system of FIG. 26 , according to some embodiments;

FIG. 31A is a schematic diagram illustrating an example of areaattributes of a tracking map (TM) and environment maps in a database,according to some embodiments;

FIG. 31B is a schematic diagram illustrating an example of determining ageographic location of a tracking map (TM) for geo-location filtering ofFIG. 29 , according to some embodiments;

FIG. 32 is a schematic diagram illustrating an example of geo-locationfiltering of FIG. 29 , according to some embodiments;

FIG. 33 is a schematic diagram illustrating an example of Wi-Fi BSSIDfiltering of FIG. 29 , according to some embodiments;

FIG. 34 is a schematic diagram illustrating an example of use oflocalization of FIG. 29 , according to some embodiments;

FIGS. 35 and 36 are block diagrams of an XR system configured to rankand merge a plurality of environment maps, according to someembodiments.

FIG. 37 is a block diagram illustrating a method of creating environmentmaps of a physical world, in a canonical form, according to someembodiments;

FIGS. 38A and 38B are schematic diagrams illustrating an environment mapcreated in a canonical form by updating the tracking map of FIG. 7 witha new tracking map, according to some embodiments.

FIGS. 39A to 39F are schematic diagrams illustrating an example ofmerging maps, according to some embodiments;

FIG. 40 is a two-dimensional representation of a three-dimensional firstlocal tracking map (Map 1), which may be generated by the first XRdevice of FIG. 9 , according to some embodiments;

FIG. 41 is a block diagram illustrating uploading Map 1 from the firstXR device to the server of FIG. 9 , according to some embodiments;

FIG. 42 is a schematic diagram illustrating the XR system of FIG. 16 ,showing the second user has initiated a second session using a second XRdevice of the XR system after the first user has terminated a firstsession, according to some embodiments;

FIG. 43A is a block diagram illustrating a new session for the second XRdevice of FIG. 42 , according to some embodiments;

FIG. 43B is a block diagram illustrating the creation of a tracking mapfor the second XR device of FIG. 42 , according to some embodiments;

FIG. 43C is a block diagram illustrating downloading a canonical mapfrom the server to the second XR device of FIG. 42 , according to someembodiments;

FIG. 44 is a schematic diagram illustrating a localization attempt tolocalize to a canonical map a second tracking map (Map 2), which may begenerated by the second XR device of FIG. 42 , according to someembodiments;

FIG. 45 is a schematic diagram illustrating a localization attempt tolocalize to a canonical map the second tracking map (Map 2) of FIG. 44 ,which may be further developed and with XR content associated with PCFsof Map 2, according to some embodiments;

FIGS. 46A-46B are a schematic diagram illustrating a successfullocalization of Map 2 of FIG. 45 to the canonical map, according to someembodiments;

FIG. 47 is a schematic diagram illustrating a canonical map generated byincluding one or more PCFs from the canonical map of FIG. 46A into Map 2of FIG. 45 , according to some embodiments;

FIG. 48 is a schematic diagram illustrating the canonical map of FIG. 47with further expansion of Map 2 on the second XR device, according tosome embodiments;

FIG. 49 is a block diagram illustrating uploading Map 2 from the secondXR device to the server, according to some embodiments;

FIG. 50 is a block diagram illustrating merging Map 2 with the canonicalmap, according to some embodiments;

FIG. 51 is a block diagram illustrating transmission of a new canonicalmap from the server to the first and second XR devices, according tosome embodiments;

FIG. 52 is block diagram illustrating a two-dimensional representationof Map 2 and a head coordinate frame of the second XR device that isreferenced to Map 2, according to some embodiments;

FIG. 53 is a block diagram illustrating, in two-dimensions, adjustmentof the head coordinate frame which can occur in six degrees of freedom,according to some embodiments;

FIG. 54 a block diagram illustrating a canonical map on the second XRdevice wherein sound is localized relative to PCFs of Map 2, accordingto some embodiments;

FIGS. 55 and 56 are a perspective view and a block diagram illustratinguse of the XR system when the first user has terminated a first sessionand the first user has initiated a second session using the XR system,according to some embodiments;

FIGS. 57 and 58 are a perspective view and a block diagram illustratinguse of the XR system when three users are simultaneously using the XRsystem in the same session, according to some embodiments;

FIG. 59 is a flow chart illustrating a method of recovering andresetting a head pose, according to some embodiments;

FIG. 60 is a block diagram of a machine in the form of a computer thatcan find application in the present invention system, according to someembodiments;

FIG. 61 is a schematic diagram of an example XR system in which any ofmultiple devices may access a localization service, according to someembodiments;

FIG. 62 is an example process flow for operation of a portable device aspart of an XR system that provides cloud-based localization, accordingto some embodiments; and

FIGS. 63A, B, and C are an example process flow for cloud-basedlocalization, according to some embodiments.

FIGS. 64, 65, 66, 67, and 68 are a sequence of schematic illustrationsof a portable XR device constructing a tracking map, with multiple tileshaving wireless fingerprints, as a user wearing the XR device, traversesthe 3D environment.

FIG. 69 is a schematic illustration of using wireless fingerprints forselecting a tile in a stored map in a set of stored maps as a candidatetile for use in localizing the portable XR device constructing thetracking map of FIGS. 64, 65, 66, 67, and 68 .

FIG. 70 is flow chart illustrating a method of operation of a portableXR device to generate wireless fingerprints according to someembodiments.

FIG. 71 is a block diagram depicting a representative system comprisinga portable device, configured for operation in a first XR system andadapted to operate in a second XR system, in accordance with someembodiments.

FIG. 72 is a flowchart depicting a representative process in which aportable device, configured to operate in a first XR system may sharespatial information with other portable devices operating in a second XRsystem through a cloud-based localization service, in accordance withsome embodiments.

FIG. 73 is a flowchart depicting a representative process in which aremote localization service may provide localization information to anXR device, in accordance with some embodiments.

FIG. 74 is a flow chart of an exemplary process that may be executed aspart of local or remote localization that utilizes location metadata,according to some embodiments.

FIG. 75 is conceptual diagram of an example of a portable devicegenerating a tracking map containing location metadata, according tosome embodiments.

FIG. 76 is a schematic illustration of using location metadata forlocalizing a portable device, according to some embodiments. FIG. 77 isa block diagram of an example architecture for a cross reality platform,according to some embodiments.

FIG. 78 is a flowchart of an exemplary process for incorporatinggeo-location data captured from devices into a geo-location database,according to some embodiments.

FIG. 79 is a flowchart of an exemplary map merge algorithm, according tosome embodiments.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedembodiments. However, one skilled in the relevant art will recognizethat embodiments may be practiced without one or more of these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures associated with eyewear, includingspatial computing headsets, and hinge systems for temple arms of eyewearhave not been shown or described in detail to avoid unnecessarilyobscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense that is as “including, but not limited to.”

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, the appearances of the phrases “in one embodiment” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedembodiments. However, one skilled in the relevant art will recognizethat embodiments may be practiced without one or more of these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures associated with virtual reality (VR),augmented reality (AR), mixed reality (MR), and extended reality (XR)systems have not been shown or described in detail to avoidunnecessarily obscuring descriptions of the embodiments. It shall benote that the terms virtual reality (VR), augmented reality (AR), mixedreality (MR), and extended reality (XR) may be used interchangeably inthe present disclosure to denote a method or system for displaying atleast virtual contents to a user via at least a wearable optics assembly12 described herein.

Described herein are methods and apparatus for providing X reality (XRor cross reality) scenes. To provide realistic XR experiences tomultiple users, an XR system must know the users' physical surroundingsin order to correctly correlate locations of virtual objects in relationto real objects. An XR system may build an environment map of a scene,which may be created from image and/or depth information collected withsensors that are part of XR devices worn by users of the XR system.

In an XR system, each XR device may develop a local map of its physicalenvironment by integrating information from one or more images collectedduring a scan at a point in time. In some embodiments, the coordinatesystem of that map is tied to the orientation of the device when thescan was initiated. That orientation may change from session to sessionas a user interacts with the XR system, whether different sessions areassociated with different users, each with their own wearable devicewith sensors that scan the environment, or the same user who uses thesame device at different times.

However, applications executing on the XR system may specify thelocation of virtual content based on persistent spatial information,such as may be obtained from a canonical map that may be accessed in ashared manner by multiple users interacting with the XR system. Thepersistent spatial information may be represented by a persistent map.The persistent map may be stored in a remote storage medium (e.g., acloud). For example, the wearable device worn by a user, after beingturned on, may retrieve from persistent storage, such as cloud storage,an appropriate stored map that was previously created and stored.Retrieving a stored map may enable use of the wearable device without ascan of the physical world with the sensors on the wearable device.Alternatively, or additionally, the system/device, upon entering a newregion of the physical world, may similarly retrieve an appropriatestored map.

Sharing data about the physical world among multiple devices may enableshared user experiences of virtual content. Two XR devices that haveaccess to the same stored map, for example, may both localize withrespect to the stored map. Once localized, a user device may rendervirtual content that has a location specified by reference to the storedmap by translating that location to a frame of reference maintained bythe user device. The user device may use this local frame of referenceto control the display of the user device to render the virtual contentin the specified location.

To support these and other functions, the XR system may includecomponents that, based on data about the physical world collected withsensors on user devices, develop, maintain, and use persistent spatialinformation, including one or more stored maps. These components may bedistributed across the XR system, with some operating, for example, on ahead mounted portion of a user device. Other components may operate on acomputer, associated with the user coupled to the head mounted portionover a local or personal area network. Yet others may operate at aremote location, such as at one or more servers accessible over a widearea network.

These components, for example, may include a map merge component thatcan identify from information about the physical world collected by oneor more user devices information that is of sufficient quality to bestored as or in a persistent map. Map merge components may receiveinputs from a user device and determines the suitability of parts of theinputs to be used to update a persistent map, which may be in canonicalform. A map merge component, for example, may also promote a local mapfrom a user device that is not merged with a persistent map to be aseparate persistent map.

Yet other components may apply transformations that transforminformation captured or described in relation to one reference frameinto another reference frame. For example, sensors may be attached to ahead mounted display such that the data read from that sensor indicateslocations of objects in the physical world with respect to the head poseof the wearer. In some embodiments, a head pose of a user may includesome or all of the location of the user, the orientation of the user,and/or the gaze direction of the user, etc. as determined by theportable computing device of the user. One or more transformations maybe applied to relate that location information to the coordinate frameassociated with a persistent environment map. Similarly, data indicatingwhere a virtual object is to be rendered when expressed in a coordinateframe of a persistent environment map may be put through one or moretransformations to be in a frame of reference of the display on theuser's head. The XR system may include components that determine thesetransformations, including a localization service that determines atransformation between a local map of a device and a stored mapaccessible to multiple XR devices.

The stored map may be represented in a canonical form that may berelated to a local frame of reference on each XR device. Therelationship between the canonical map and a local map for each devicemay be determined through a localization process. The relationship maybe used to enable the device to use its local map to render content inlocations specified relative to the canonical map. Alternatively, oradditionally, a relationship between a local map and a canonical map mayenable merging of the local map into a set of canonical maps—either byupdating or extending an existing canonical map or by determining thatthe local map depicts a region for which no canonical map exists andadding the local map as a new canonical map to a set of stored canonicalmaps. In some embodiments, a canonical form (which may also bereferenced as a normal form or a standard form) of a mathematical orprogramming object resents that mathematical or programming object as amathematical expression and may provide a simpler or the simplestrepresentation of an object so as to allow the mathematical orprogramming object to be uniquely identified. In some embodiments, theterms “canonical form’ and “normal form” may be used interchangeably. Insome other embodiments, a canonical form may specify a uniquerepresentation for an object, while a normal form may specify its form,without the requirement of uniqueness. In some embodiments, a canonicalform includes a representation such that an object has a uniquerepresentation that may be determined by, for example, thecanonicalization process. In some embodiments, canonicalization (mayalso be referred to as standardization or normalization) includes aprocess for converting data that has more than one possiblerepresentation into a “standard”, “normal”, or “canonical” form. In someof these embodiments, canonicalization may be performed to, for example,compare different representations for equivalence, to count the numberof distinct data structures, to improve the efficiency of variousalgorithms by eliminating repeated calculations, or to impose ameaningful sorting order. In some embodiments, a canonical form in a setof objects having an equivalence relation represents an equivalenceclass, once and only once, such that each object in the set of objectsis equivalent to exactly one object in canonical form. In theseembodiments, a canonical form classifies every class and provides adistinct or canonical representative for each object in the class, andeach object in a given class has a single canonical representationmatching the template of the canonical form. In some embodiments, acanonical map comprises a map, transform, or morphism between objectsand arises from the definition or the construction of the objects. Amorphism includes a structure-preserving map or data structure from onestructure (e.g., an object) to another one having the same type. In someembodiments, a morphism includes one or more functions such as lineartransformations, a group homomorphism, a continuous function, etc. Insome of these embodiments, a canonical map includes a map that preservesa wider or the widest amount of structure, and the canonical map isunique. A canonical map may include one or more functions or transformsthat map a set A of objects to the set A/R (A modulo R), where Rincludes an equivalence relation on the set A. A canonical map mayinclude a two-dimensional (2D) canonical map, a three-dimensional (3D)canonical map, or a combination thereof.

The localization process may be performed on each XR device based atleast in part on a set of canonical maps selected and sent to thedevice. Alternatively, or additionally, localization may be performed bya localization service, which may be implemented on remote processors,such as might be deployed in the cloud. During a use of a map tolocalize a user, a camera or sensor of a portable computing device(e.g., an XR headset) may obtain an image of the environment based atleast in part on, for example, a certain position and orientation of theuser. Such camera or sensor image serves as a tracking image (trackingmap) for allowing the processing unit of the image display device totrack a position of the user.

It shall be noted that such camera or sensor image serving as a trackingmap may or may not be a photograph as generally captured by cameras.Rather, a tracking map may only include just enough image or sensor dataof the environment so that such image or data may be used to track theposition, orientation, and/or headpose of the user. For example, atracking map may represent a location, an object, a fingerprint of alocation (e.g., the GPS data or a histogram of a location), or a featureof an object, etc. as a node associated with annotation or metadataindicating the location, object, fingerprint, or a feature of an object,etc. represented with the node in relation to, for example, a referenceor absolute reference coordinate system and/or a reference headpose.

In some other embodiments, a tracking map may in particular, theprocessing unit of the portable computing device processes the imagefrom the camera to determine whether one or more features in the imagematch with one or more corresponding features in the map. If a match isfound, the processing unit may then determine the position andorientation of the user based at least in part on the matchedfeature(s). In some embodiments, the map may include less information(e.g., features) than the tracking image provided by the camera of theimage display device. This may be advantageous because such a map havingless information allows the processing unit to more efficiently matchthe tracking image with the map. In some embodiments, the map may becalled a “canonical map”. When performing localization, the processingunit performs features extraction to extra features from camera image(tracking image), and matches the features with those in the canonicalmap.

In one implementation, the processing unit may be configured to find asix degree of freedom transformation (e.g., translation as well asrotation along the x-, y-, and z-axis) between the tracking image andthe canonical map to localize the user. Once the user may besuccessfully localized with respect to the user's environment using themap, the processing unit may then allow the user to place virtualcontent with respect to the environment using the map, retrieve thevirtual content from previous session, share the virtual content withother user(s), etc. In some embodiments, a canonical map includes one ormore structures (e.g., objects) that include one or more persistentcoordinate frames (PCFs) that are stored within the canonical map or areotherwise stored separately in a data structure and are associated withthe one or more structures.

A structure (e.g., object) represented in a canonical map may include asingle PCF node having the persistent coordinate frame information andrepresenting an object in some embodiments. In some other embodiments, astructure represented in a canonical map may include multiple PCFs eachof which is a local coordinate frame relative to, for example, areference system of coordinates of a device that generated or updatedthe canonical map. Moreover, these multiple PCFs may respectivelyrepresent multiple corresponding features of the object. In someembodiments, the morphism or one or more functions defined for and/orincluded in a canonical frame may further comprise one or moreoperations that receive an input (e.g., input location, orientation,pose, surface, coordinate system, and/or depth information) from, forexample, a tracking map, a sparse map, a dense map, etc. and generate anoutput for the input by performing a transformation (e.g., a matrixoperation for translation, rotation, mirroring, etc.) In someembodiments, a canonical map includes only a morphism (or one or morefunctions) and one or more structure each represented by one or morepersistent coordinate frames but no other data or information. In someother embodiments, a canonical map includes a morphism, one or morestructures each represented by one or more persistent coordinate frames,and data or metadata corresponding to a description or characteristic ofthe structure. More details about a persistent coordinate frame arefurther described below.

In some embodiments, the persistent maps may be constructed frominformation collected by multiple user devices in a map merge process.The XR devices may each capture local spatial information and constructseparate tracking maps with information collected by sensors of each ofthe XR devices at various locations and times. Each tracking map mayinclude information about persistent locations, each of which may beassociated with one or more features of one or more real objects. A userdevice may track its location relative to these persistent locations byfinding in current images of the physical world a set of features thatmatch features associated with a persistent location in the map. Duringa session, the tracking maps may be used to track users' motions in thephysical world, enabling an XR system to estimate respective users'headposes relative to the frame of reference established by the trackingmap on that user's device. As the device moves through the physicalworld, it may capture images of the physical world, creating more setsof features that can be appended to the tracking map.

At the end of a session, or from time to time during a session, aportable device may send all or part of the tracking map to a map mergeservice. The map merge service may match a portion of the tracking mapto a portion of a canonical map (which may start as a separate trackingmap in some embodiments) and then merge the tracking map into thecanonical map. As with localization, the merge process entails matchinglocation information from a device with a portion of a stored map. Inthe case of a merge operation, the location information from the deviceis formatted as a tracking map.

Regardless of where the localization is performed, the inventors haverecognized and appreciated that the efficient selection of one or asmall number of canonical maps, or more specifically one or moresegments of the canonical map with which to attempt localization or mapmerging, may reduce computational requirements and latency for thelocalization or map merge process. As a result, localization and mapmerge may be completed more quickly, more frequently and/or with lowerpower consumption such that virtual content may be displayed with lesslatency or more accuracy, creating a more immersive user experience.

In some embodiments, matching location information from a device to aportion of a stored canonical map may be made more efficient by storinglocation metadata in connection with segments of the universe ofcanonical maps available for localization or merging. A portable devicemay obtain or maintain location metadata in connection with its localmap. That location metadata may be used to select a set of candidatesegments of the set of canonical maps for use in attempting the matchingprocess or to quickly determine that no suitable canonical map segmentexists. Location metadata may include data pertaining to some or all ofthe location of an object or point of interest, the orientation of theobject or point of interest, and/or the gaze direction of the object orpoint perceived by a user, etc. as determined by the portable computingdevice of the user.

The inventors have further recognized and appreciated, however, thatdifferent types of information from which location metadata can bederived may be available on different types of portable devicesinteracting with an XR system. Further, these different types ofinformation may lead to different effectiveness in selecting a set ofcandidate map segments.

Some portable devices, for example, may maintain wireless fingerprintsassociated with persistent locations in their local maps, which mayserve as location metadata. Maintaining the wireless fingerprints mayentail repetitively updating a wireless fingerprint associated with thetracking map as the device moves throughout a region of the physicalworld. Updating in this way may enable filtering and averaging wirelesscharacteristics within regions of the physical world in the vicinity oflocations represented by persistent poses. Such processing may result instable and accurate wireless fingerprints, which in turn may lead tomore accurate matching with other, similarly created wirelessfingerprints. Moreover, such a process increases the availability ofwireless fingerprints, reducing latency associated with localizationprocessing. With more efficient localization, there is a greater abilitywithin a system for sharing data about the physical world among multipledevices.

Other portable devices may have access to GPS data. Yet, other devicesmay alternatively or additionally have an operating system that providesan API that, when accessed, provides geolocation information. Yet otherdevices may alternatively or additionally, upon localization with acanonical map for which geolocation information is available, storelocation information derived from the canonical map to which it waslocalized. In a subsequent localization or map merge attempt, this priorlocalization information may be used to select candidate map segments.In scenarios in which some or all of the processing is performed on aserver, some or all of this location information may be stored by theserver such that it need not be sent with from the portable device foruse in selecting candidate maps.

A service, using location metadata in conjunction with local mapinformation from a portable XR device—whether for localizing the devicewith respect to a canonical map or for merging the local map with theset of canonical maps—may prioritize one type of location metadata overothers. The prioritization may be based on the effectiveness of theselection of candidate map segments using each type of locationmetadata. Location metadata derived from a prior localization may begiven high priority, for example. As another example, a wirelessfingerprint may be given a lower priority than a prior localization, buta higher priority than geolocation information obtained through anoperating system API. In other embodiments, where direct access to a GPSdata is available, GPS data may be given higher priority.

Such a service may contain components to facilitate selection of mapsegments based on location metadata. Those components may include acomponent to translate between formats of the metadata, such astranslating a wireless signature into latitude and longitude tofacilitate comparison to geolocation information obtained from anoperating system API. The location metadata from multiples sources, forexample, may be converted to a common format such as a geohash.Alternatively, or additionally, such a service may include componentsthat efficiently select map segments based on metadata associated with aportable device. The service, for example, may maintain an index linkinggeohashes to map segments, such that map segments proximate a locationidentified by location metadata for a portable device can be quicklyselected.

Efficient selection of sub-portions of a canonical map, enables mapmerging operations to be performed over those sub-portions. Because asub-portion of a canonical map is smaller than the entire canonical map,performing map merge algorithms in this fashion requires lesscomputational power, enabling canonical maps to be generated morequickly and more accurately without excessive processing resources.

Techniques as described herein may be used together or separately withmany types of devices and for many types of scenes, including wearableor portable devices with limited computational resources that provide anaugmented or mixed reality scene. In some embodiments, the techniquesmay be implemented by one or more services that form a portion of an XRsystem.

AR System Overview

FIGS. 1 and 2 illustrate scenes with virtual content displayed inconjunction with a portion of the physical world. For purposes ofillustration, an AR system is used as an example of an XR system. FIGS.3-6B illustrate an exemplary AR system, including one or moreprocessors, memory, sensors and user interfaces that may operateaccording to the techniques described herein.

Referring to FIG. 1 , an outdoor AR scene 354 is depicted in which auser of an AR technology sees a physical world park-like setting 356,featuring people, trees, buildings in the background, and a concreteplatform 358. In addition to these items, the user of the AR technologyalso perceives that they “see” a robot statue 357 standing upon thephysical world concrete platform 358, and a cartoon-like avatarcharacter 352 flying by which seems to be a personification of a bumblebee, even though these elements (e.g., the avatar character 352, and therobot statue 357) do not exist in the physical world. Due to the extremecomplexity of the human visual perception and nervous system, it ischallenging to produce an AR technology that facilitates a comfortable,natural-feeling, rich presentation of virtual image elements amongstother virtual or physical world imagery elements.

Such an AR scene may be achieved with a system that builds maps of thephysical world based on tracking information, enable users to place ARcontent in the physical world, determine locations in the maps of thephysical world where AR content are placed, preserve the AR scenes suchthat the placed AR content can be reloaded to display in the physicalworld during, for example, a different AR experience session, and enablemultiple users to share an AR experience. The system may build andupdate a digital representation of the physical world surfaces aroundthe user. This representation may be used to render virtual content soas to appear fully or partially occluded by physical objects between theuser and the rendered location of the virtual content, to place virtualobjects, in physics-based interactions, and for virtual character pathplanning and navigation, or for other operations in which informationabout the physical world is used.

Various embodiments described herein employ one or more of maps that mayinclude, without limitation, one or more sparse maps, one or more densemaps, one or more tracking maps, one or more canonical maps, and/or oneor more environment maps.

A tracking map may be local to the device (e.g., an XR device) thatoriginally created or subsequently updated the tracking map. A trackingmap may serve as a dense map although a tracking map may start as asparse map. A tracking map may include data such as headpose data of adevice (e.g., the location, orientation, and/or pose of an XR devicecreating or updating the tracking map) in some embodiments. Such datamay be represented as a point or a point node in a tracking map in someof these embodiments.

In some of these embodiments, a tracking map may further include surfaceinformation or data that may be represented as a set of meshes or depthinformation and/or other high-level data (e.g., location and/or one ormore characteristics pertaining to one or more planes or surfaces orother objects) that may be derived from the surface or depthinformation. A tracking map may be promoted to a canonical map whichwill be described in greater details below. In some embodiments, atracking map provides a floorplan of physical objects in the physicalworld. For example, a physical object or a feature thereof (e.g., avertex, an edge, a plane or surface, etc. determined from imageprocessing) may be represented as a point or point node in a trackingmap.

In some of these embodiments, a tracking map may include data pertainingto a point or point node. Such data may include, for example, absoluteand/or relative poses (e.g., absolute location, orientation, and/or gazedirection relative to a known, fixed reference, relative location,orientation, and/or gaze direction relative to an XR device at aparticular location, orientation, and/or gaze direction). A featurerepresenting a physical object or a portion thereof may be derived from,for example, image processing of one or more images containing thephysical object or the portion thereof and may be used as a persistentpose that in turn may be transformed into a persistent coordinate frame(PCF). In some embodiments, a persistent coordinate frame comprises alocal coordinate frame (e.g., a coordinate frame local to a referencepoint or coordinate system of an XR device) that allows contentpersistence—placement of digital contents in a virtual or mixed-realityenvironment and have the placed digital contents stay in the samelocation(s) in, for example, the virtual- or mixed-reality environment(e.g., a passable world model, a shared world model, and/or one or moremaps described herein), without drifts or deviations beyond a predefinedthreshold across multiple user sessions (for one or more XR devices)even after closing, re-opening an application or rebooting of XRdevice(s).

A PCF may be placed in, for example, a canonical map described herein ata specific location, in a specific orientation, and/or in a particulargaze direction from the perspective of the viewing XR device that firstcreates the PCF to represent an object or a portion thereof. When an XRdevice enters a physical environment that the XR device or anothercollaborating XR device has already seen before (e.g., via one or moreimages captured by the XR device or another collaborating XR device),the persistent coordinate frames placed for this physical environmentmay be restored in the correct location(s) by the XR device byretrieving one or more corresponding canonical maps created for at leasta portion of the physical environment.

In some embodiments, a PCF corresponds to a predefined position in thephysical world and has a unique identifier which a user may store in abrowser session, on the portable computing device (e.g., an XR device),or on a remote server. This unique identifier may be shared amongmultiple users. For example, when a digital content is placed in avirtual- or mixed-reality session, the nearer or nearest PCF may berequested, and the unique identifier of the nearer or the nearest PCF aswell as the location corresponding to the PCF may be stored.

When the PCF is reused in a different session for a user at a differentlocation, this stored location corresponding to the PCF may betransformed (e.g., translation, rotation, mirroring, etc.) with respectto the current coordinate system for the different location for thedifferent virtual- or mixed-reality session so that the digital contentis placed at the correct location relative to the user in the differentsession. A PCF may store persistent spatial information in someembodiments. In some of these embodiments, a PCF may further include atransformation relative to a reference location, orientation, and/orgaze direction as well as information derived from one or more images ata location that corresponds to the PCF. For example, a PCF may includeor may be at least associated with a transformation between a coordinateframe of a map (e.g., a tracking map, a canonical map, an environmentmap, a sparse map, and/or a dense map, etc.) and the PCF.

In some of these embodiments, a PCF may include geographic or spatialinformation indicating a location within a 3D environment of a keyframeor image frame from which the persistent coordinate frame is created. Insome embodiments, the transformation may be determined between acoordinate frame local to the portable computing device (e.g., an XRdevice) and a stored coordinate frame.

In some embodiments, all PCFs are sharable and can be transmitted amongmultiple users at respective, different locations. In some otherembodiments, one or more PCFs are only known to an XR device that firstcreated these one or more PCFs. In some embodiments, information aboutthe physical world, for example, may be represented as persistentcoordinate frames (PCFs). A PCF may be defined based on one or morepoints that represent features recognized in the physical world. Thefeatures may be selected such that they are likely to be the same fromuser session to user session of the XR system. PCFs may exist sparsely,providing less than all of the available information about the physicalworld, such that they may be efficiently processed and transferred.

As a practical working example of a room having two XR devices (device Aand device B) and a digital object, if the user of XR device A placesthe digital content somewhere in the room and sets the digital contentto persist, meaning that the digital content stays at the samereal-world position for XR device B. Both users may see the digitalcontent in front of them. Both devices use position (e.g., x=0, y=0,z=0) as their world origin, the location where both users boot up theirrespective XR devices so the digital content is located in position(x=0, y=0, z=1) for both XR devices. The challenge is that the two XRdevices may have different world coordinate systems because these two XRdevices may have been turned on at different locations and/or indifferent orientations. For example, if XR device B faces the oppositedirection when booting up then the digital content should be in (0, 0,1) for XR device A and (0, 0, −1) for XR device B. If the user of XRdevice A generated the digital content, an application execution on bothXR devices A and B may link (0, 0, 1) of XR device A to (0, 0, −1) of XRdevice B.

Persistent coordinate frames (PCFs) may be used to anchor digitalcontent to the real world by indirectly referring to space. PCFs mayinclude one or more spatial anchors that have a persistent position andorientation in the environment in some embodiments. Applications mayquery for PCFs in the users' environment and decide which PCF(s) toattach virtual content to. When two collocated devices recognize thespace the two devices are in, they may both have access to the PCFs of amap (e.g., a canonical map stored on the cloud). The fact that the worldorigins differ may not affect this process. An application running on anXR device may retrieve the position and orientation of the PCF(s) “seen”by this XR device in relation to the XR device's world origin. The samePCF(s) seen by two collocated devices may have different positions andorientations with respect to each XR device's world origin. In terms ofthe real world, however, a PCF has only one specific position andorientation.

The relative position and orientation of the digital object to the PCFdoes not depend on the world origin of the collocated devices. So, thedigital potted plant persists and gets the correct position andorientation for both devices if an application (a) uses the same commonPCF for this particular digital object; (b) calculates the relativeposition and orientation of the digital object to this PCF; and/or (c)shares these values between devices in some embodiments. Moreover, a PCFhas a unique identifier. In some embodiments, all maps referenced by anXR device may have or reference at least one PCF; and localized deviceswithin the same map have access to every PCF of that map (e.g., acanonical map stored in the cloud or a remote server).

A persistent coordinate frame (PCF) includes a local coordinate framethat allows a user to place digital content in the physical world andhave the digital content stay in the same place without any drift acrossmultiple user sessions of one or more XR devices. PCFs May beautomatically adjusted so any digital content placed relative to a PCFmaintains its exact position in the real world. When an XR devicerecognizes that the XR device is in a space it has seen before, any PCFsplaced in the space may be restored in some embodiments so that anycontent placed relative to a PCF may be persisted across multiplereboots. PCFs may be automatically synchronized among users who are inthe same space so multiple users may see the same content in the samephysical location.

PCFs may be created and managed automatically so an application does notneed to do anything special to make, save, or restore a PCF in someembodiments. PCFs may be automatically restored at or near the correctlocation when an XR device recognizes that the XR device is in a spacepreviously mapped. In some embodiments, applications may use PCFs thatare within 4 to 5 meters from where the applications want to placedigital content, and these applications may reattach digital content toa closer or the closest PCF when the digital content is moved. A usermay use persistent coordinate frames in the user's XR softwareapplications to provide local coordinate frames that anchor digitalcontent in the real world without any or perceivable (e.g., perceivableby a user) drift between multiple sessions.

Techniques for processing persistent spatial information may includecreating dynamic maps based on one or more coordinate systems in realspace across one or more sessions, and generating persistent coordinateframes (PCF) over the sparse maps, which may be exposed to XRapplications via, for example, an application programming interface(API). These capabilities may be supported by techniques for ranking andmerging multiple maps created by one or more XR devices. Persistentspatial information may also enable quickly recovering and resettinghead poses on each of one or more XR devices in a computationallyefficient way. In some embodiments, an XR system may assign a coordinateframe to a virtual content, as opposed to attaching the virtual contentin a world coordinate frame. Such configuration enables a virtualcontent to be described without regard to where it is rendered for auser, but it may be attached to a more persistent frame position such asa persistent coordinate frame (PCF) to be rendered in a specifiedlocation. When the locations of the objects change, the XR device maydetect the changes in the environment map and determine movement of thehead unit worn by the user relative to real-world objects.

In some embodiments, spatial persistence may be provided throughpersistent coordinate frames (PCFs). A PCF may be defined based on oneor more points, representing features recognized in the physical world(e.g., corners, edges). The features may be selected such that they arelikely to be the same from a user instance to another user instance ofan XR system. In addition or in the alternative, drift during tracking,which causes the computed tracking path (e.g., camera trajectory) todeviate from the actual tracking path, can cause the location of virtualcontent, when rendered with respect to a local map that is based solelyon a tracking map to appear out of place. A tracking map for the spacemay be refined to correct the drifts as an XR device collects moreinformation of the scene overtime. However, if virtual content is placedon a real object before a map refinement and saved with respect to theworld coordinate frame of the device derived from the tracking map, thevirtual content may appear displaced, as if the real object has beenmoved during the map refinement. PCFs may be updated according to maprefinement because the PCFs are defined based on the features and areupdated as the features move during map refinements.

In some embodiments, a PCF may comprise six degrees of freedom withtranslations and rotations relative to a map coordinate system. A PCFmay be stored in a local and/or remote storage medium. The translationsand rotations of a PCF may be computed relative to a map coordinatesystem depending on, for example, the storage location. For example, aPCF used locally by a device may have translations and rotationsrelative to a world coordinate frame of the device. A PCF in the cloudmay have translations and rotations relative to a canonical coordinateframe of a canonical map. In some embodiments, PCFs may provide a sparserepresentation of the physical world, providing less than all of theavailable information about the physical world, such that they may beefficiently processed and transferred. Techniques for processingpersistent spatial information may include creating dynamic maps basedon one or more coordinate systems in real space across one or moresessions, generating persistent coordinate frames (PCF) over the sparsemaps, which may be exposed to XR applications via, for example, anapplication programming interface (API).

In some embodiments, a tracking map may include one or more imageframes, keyframes, etc. and/or data derived from one or more imageframes, keyframes, etc. It shall be noted that not all features andimage frames (or keyframes) may be retained as a part of a tracking map.Rather, feature points or image frames that provide meaningfulinformation (e.g., non-redundant information, information withsufficiently high accuracy and/or resolution beyond a predefinedthreshold value, etc.) may be retained in a tracking map. Therefore, atracking map may be constructed with data collected or gathered by oneor more cameras, image sensors, depth sensors, GPS (global positioning)devices, wireless devices (e.g., a Wi-Fi or a cellular transceiver),etc.

A tracking map may be stored as or merged with an environment map whichwill also be described in greater details below. A tracking map may berefined to correct, for example, any deviations or drifts of a computedtracking path (e.g., a computed camera trajectory) that deviates fromthe actual tracking path. In some embodiments, images providingmeaningful information to a tracking map may be selected as keyframesthat may further be integrated within (e.g., embedded within a trackingmap) or associated with (e.g., stored separated yet linked with atracking map) a tracking map. In some embodiments, a tracking map may beconnected to or associated with a pose and a PCF (persistent coordinateframe) transformer.

A sparse map may include data that indicates a location of a point orstructure of interest (e.g., a corner, an edge, a surface, etc.) insteadof all the locations of features in some embodiments. That is, certainpoints or structures in a physical environment may be discarded from asparse map. A sparse map may be constructed with a set of mapped pointsand/or keyframes of interest by, for example, image processing thatextracts one or more points or structures of interest. One example of asparse may include a tracking map described above. In this example, thetracking map may be deemed as a headpose sparse map although it shall benoted that other sparse maps may not always include headpose data. Asparse map may include information or data that may be used to derive acoordinate system in some embodiments. In some other embodiments, asparse map may include or may be associated with a coordinate system.Such a coordinate system may be used to define the position and/ororientation of an object or a feature thereof in a dense map that willbe described in greater details below.

A dense map may include, for example, data or information such assurface data represented by mesh or depth information in someembodiments. In some of these embodiments, a dense map may includehigh-level information that may be derived from surface or depthinformation. For example, a dense map may include data pertaining to thelocation and/or one or more characteristics of a plane and/or otherobject(s). A dense map may be augmented from a sparse map by augmentingthe original data of the sparse map with any of the aforementioned dataor information although it shall be noted that sparse maps may becreated independently of the creation of dense maps, and vice versa, insome embodiments.

An environment map may include data or information of a piece of aphysical world. For example, an environment may include locations,orientations, and/or gaze directions (when perceived with an XR device)of physical objects in a physical environment (e.g., a portion of aroom) as well as other data pertaining to the physical objects (e.g.,surface textures, colors, etc.) An environment map may be created withdata from, for example, images from camera(s) and/or depth data fromdepth sensor(s). An environment may thus include much more details aboutthe physical environment than any other maps described herein and may beused to construct a passable 3D world that may be collaborated upon(e.g., created by multiple XR devices moving around the physical world)and shared among multiple XR devices.

An environment map may be transformed or stripped into a canonical mapby, for example, removing unneeded data or information in someembodiments. An environment map may also be associated with multiplearea or volume attributes such as one or more parameters, strengths ofreceived signals, etc. of wireless networks, or any other desired orrequired parameters. Construction of a passable 3D world and contentpersistence (e.g., by using various maps, persistent coordinate frames,etc.) provide a spatialized experience while shareable worldconstruction replicates aspects of the physical world, persistence“places” digital contents in physical space as if these digital contentswere a part of the physical space. A content persistence process assignsa position and rotation relative to the physical world, retains positionand rotation regardless of the status of XR devices (e.g., XR devicesbeing turned on/off, application(s) being closed, or rebooting XRdevices may not affect users' perception of contents as the contents arealways “there”). Content persistence further allows users to experience,interact with, and/or share, etc. the same contents and confirms thecontents are “there” in the physical world, and acknowledges that everyuser around witnesses the same.

Content persistence may be based at least in part upon the followingelements—headpose and a passable world model or map in some embodiments.In some embodiments, headpose monitors user movement in physical spaceby tracking the location of the XR device worn by the user withreference to a position where the XR device was turned on (e.g., a worldorigin). In some embodiments where an XR device is turned on in anarbitrary position (e.g., the local origin x=0, y=0, z=0), and the userwalks one (1) unit along the x-axis, the final position of Headpose willbe (1, 0, 0). In some of these embodiments, headpose may further monitorthe orientation of a user or the gaze direction of the user (e.g., viainward facing camera(s) tracking the movement(s) of the eye(s) orpupil(s) with an 2D or 3D eye model). A passable world model may persistdigital contents and unify real world data collected by multiplesessions and one or more XR devices in some embodiments. A user'sconsent may be required in order to collect such data in someembodiments. Headpose maps the world around the user. A passable worldmap or model decides whether spatial data sent by headpose belong topreviously stored and localized map(s) such as one or more mapsdescribed herein. A passable world map or model may create one or morenew maps and merge overlapping maps.

A canonical map may include data or information so that the canonicalmap may be localized and oriented to each of a plurality of computingdevices so that each computing device may reuse the canonical map. Acanonical map may thus originate as a tracking map or a sparse in someembodiments or as an environment map in some other environment.

A canonical map may include or may be associated with just enough datathat determines a location of an object represented in the canonical mapin some embodiments. For example, a canonical map may include or may beassociated with persistent pose(s) and/or persistent coordinate frame(s)of an object of interest or a portion thereof. A canonical map, like anyother maps described herein, may be merged with, for example, thepersistent coordinate frame(s) in another map to render a new canonicalmap (e.g., by using a map merge algorithm 124).

A canonical map that has been localized to a specific XR device may bereferred to as a promoted map. In some embodiments, a canonical mapincludes coordinate information (e.g., coordinates of a point, acoordinate system, etc.) and may also include one or more structuresthat include, for example, at least one PCF (persistent coordinateframe). For localizing a tracking map, an image frame or a keyframepertaining to the tracking map may be associated with the at least onePCF pertaining to the canonical map; and the pose of the image may thenbe used to localize the tracking map that stores the pose information.

Canonical maps may be ranked with respective rankings that may indicatecanonical maps that have regions similar to a region of the tracking mapsuch that, upon attempting to merge the tracking map into the canonicalmap, it is like that there will be a correspondence between at least aportion of the tracking map and at least a portion of the canonical map.A canonical map may have one or more tiles or defined areas; and mergingthe canonical map with another map may be limited to one or more tilesor defined areas to conserve computing resource consumption.

A canonical map may include a set of features that defines one or morepersistent coordinate frames (PCFs) in some embodiments although thereis no requirement that the set of features be associated with a singlepersistent location in either the canonical map or the tracking map. Insome embodiments, a transformation of the set of feature points in thetracking map to align with the candidate set of features in thecanonical map. This transformation may be applied to the entire trackingmap, enabling overlapping portions of the tracking map and the canonicalmap to be identified.

Multiple canonical maps may be merged to render a new canonical map. Insome embodiments, the attributes of a canonical map may be derived fromthe attributes of a tracking map or maps used to form an area of thecanonical map. In some embodiments in which a persistent coordinateframe of a canonical map is defined based on a persistent pose in atracking map that was merged into the canonical map, the persistentcoordinate frame may be assigned the same attributes as the persistentpose. In some embodiments, a canonical map may include apluralityattributes serving as canonical map identifiers indicating thecanonical map's location within a physical space, such as somewhere onthe planet earth or in the space.

In some embodiments, multiple canonical maps may be disposedgeographically in a two-dimensional pattern as these multiple canonicalmaps may exist on a surface of the earth (or in the space). Thesecanonical maps may be uniquely identifiable by, for example,corresponding longitudes and latitudes or positions relative to earth.In these embodiments, these canonical maps may provide a floorplan ofreconstructed physical objects in a corresponding physical world,represented by respective points. A map point in a canonical map mayrepresent a feature of a physical object that may include multiplefeatures. In some embodiments where a server stores no canonical map fora region of the physical world represented by the tracking map, thetracking map may be stored as an initial canonical map that may furtherbe processed to become a canonical map having the pertinent data, whenavailable.

FIG. 2 depicts another example of an indoor AR scene 400, showingexemplary use cases of an XR system, according to some embodiments. Theexemplary scene 400 is a living room having walls, a bookshelf on oneside of a wall, a floor lamp at a corner of the room, a floor, a sofa,and coffee table on the floor. In addition to these physical items, theuser of the AR technology also perceives virtual objects such as imageson the wall behind the sofa, birds flying through the door, a deerpeeking out from the book shelf, and a decoration in the form of awindmill placed on the coffee table.

For the images on the wall, the AR technology requires information aboutnot only surfaces of the wall but also objects and surfaces in the roomsuch as lamp shape, which are occluding the images to render the virtualobjects correctly. For the flying birds, the AR technology requiresinformation about all the objects and surfaces around the room forrendering the birds with realistic physics to avoid the objects andsurfaces or bounce off them if the birds collide. For the deer, the ARtechnology requires information about the surfaces such as the floor orcoffee table to compute where to place the deer. For the windmill, thesystem may identify that is an object separate from the table and maydetermine that it is movable, whereas corners of shelves or corners ofthe wall may be determined to be stationary. Such a distinction may beused in determinations as to which portions of the scene are used orupdated in each of various operations.

The virtual objects may be placed in a previous AR experience session.When new AR experience sessions start in the living room, the ARtechnology requires the virtual objects being accurately displayed atthe locations previously placed and realistically visible from differentviewpoints. For example, the windmill should be displayed as standing onthe books rather than drifting above the table at a different locationwithout the books. Such drifting may happen if the locations of theusers of the new AR experience sessions are not accurately localized inthe living room. As another example, if a user is viewing the windmillfrom a viewpoint different from the viewpoint when the windmill wasplaced, the AR technology requires corresponding sides of the windmillbeing displayed.

A scene may be presented to the user via a system that includes multiplecomponents, including a user interface that can stimulate one or moreuser senses, such as sight, sound, and/or touch. In addition, the systemmay include one or more sensors that may measure parameters of thephysical portions of the scene, including position and/or motion of theuser within the physical portions of the scene. Further, the system mayinclude one or more computing devices, with associated computerhardware, such as memory. These components may be integrated into asingle device or may be distributed across multiple interconnecteddevices. In some embodiments, some or all of these components may beintegrated into a wearable device.

FIG. 3 depicts an AR system 502 configured to provide an experience ofAR contents interacting with a physical world 506, according to someembodiments. The AR system 502 may include a display 508. In theillustrated embodiment, the display 508 may be worn by the user as partof a headset such that a user may wear the display over their eyes likea pair of goggles or glasses. At least a portion of the display may betransparent such that a user may observe a see-through reality 510. Thesee-through reality 510 may correspond to portions of the physical world506 that are within a present viewpoint of the AR system 502, which maycorrespond to the viewpoint of the user in the case that the user iswearing a headset incorporating both the display and sensors of the ARsystem to acquire information about the physical world.

AR contents may also be presented on the display 508, overlaid on thesee-through reality 510. To provide accurate interactions between ARcontents and the see-through reality 510 on the display 508, the ARsystem 502 may include sensors 522 configured to capture informationabout the physical world 506.

The sensors 522 may include one or more depth sensors that output depthmaps 512. Each depth map 512 may have multiple pixels, each of which mayrepresent a distance to a surface in the physical world 506 in aparticular direction relative to the depth sensor. Raw depth data maycome from a depth sensor to create a depth map. Such depth maps may beupdated as fast as the depth sensor can form a new image, which may behundreds or thousands of times per second. However, that data may benoisy and incomplete, and have holes shown as black pixels on theillustrated depth map.

The system may include other sensors, such as image sensors. The imagesensors may acquire monocular or stereoscopic information that may beprocessed to represent the physical world in other ways. For example,the images may be processed in world reconstruction component 516 tocreate a mesh, representing connected portions of objects in thephysical world. Metadata about such objects, including for example,color and surface texture, may similarly be acquired with the sensorsand stored as part of the world reconstruction.

The system may also acquire information about the headpose (or “pose”)of the user with respect to the physical world. In some embodiments, ahead pose tracking component of the system may be used to computeheadposes in real time. The head pose tracking component may represent aheadpose of a user in a coordinate frame with six degrees of freedomincluding, for example, translation in three perpendicular axes (e.g.,forward/backward, up/down, left/right) and rotation about the threeperpendicular axes (e.g., pitch, yaw, and roll). In some embodiments,sensors 522 may include inertial measurement units (“IMUs”) that may beused to compute and/or determine a headpose 514. A headpose 514 for adepth map may indicate a present viewpoint of a sensor capturing thedepth map with six degrees of freedom, for example, but the headpose 514may be used for other purposes, such as to relate image information to aparticular portion of the physical world or to relate the position ofthe display worn on the user's head to the physical world.

In some embodiments, the headpose information may be derived in otherways than from an IMU, such as from analyzing objects in an image. Forexample, the head pose tracking component may compute relative positionand orientation of an AR device to physical objects based on visualinformation captured by cameras and inertial information captured byIMUs. The head pose tracking component may then compute a headpose ofthe AR device by, for example, comparing the computed relative positionand orientation of the AR device to the physical objects with featuresof the physical objects. In some embodiments, that comparison may bemade by identifying features in images captured with one or more of thesensors 522 that are stable over time such that changes of the positionof these features in images captured over time can be associated with achange in headpose of the user.

The inventors have realized and appreciated techniques for operating XRsystems to provide XR scenes for a more immersive user experience suchas estimating head pose at a frequency of 1 kHz, with low usage ofcomputational resources in connection with an XR device, that may beconfigured with, for example, four video graphic array (VGA) camerasoperating at 30 Hz, one inertial measurement unit (IMU) operating at 1kHz, compute power of a single advanced RISC machine (ARM) core, memoryless than 1 GB, and network bandwidth less than 100 Mbp. Thesetechniques relate to reducing processing required to generate andmaintain maps and estimate head pose as well as to providing andconsuming data with low computational overhead. The XR system maycalculate its pose based on the matched visual features. U.S. patentapplication Ser. No. 16/221,065 describes hybrid tracking and is herebyincorporated herein by reference in its entirety.

In some embodiments, the XR device may construct a map from the featurepoints recognized in successive images in a series of image framescaptured as a user moves throughout the physical world with the XRdevice. Though each image frame may be taken from a different pose asthe user moves, the system may adjust the orientation of the features ofeach successive image frame to match the orientation of the initialimage frame by matching features of the successive image frames topreviously captured image frames. Translations of the successive imageframes so that points representing the same features will matchcorresponding feature points from previously collected image frames, maybe used to align each successive image frame to match the orientation ofpreviously processed image frames. The frames in the resulting map mayhave a common orientation established when the first image frame wasadded to the map. This map, with sets of feature points in a commonframe of reference, may be used to determine the user's pose (and/orlocation) within the physical world by matching features from currentimage frames to the map. In some embodiments, this map may be called atracking map.

In addition to enabling tracking of the user's pose within theenvironment, this map may enable other components of the system, such asworld reconstruction component 516, to determine the location ofphysical objects with respect to the user. The world reconstructioncomponent 516 may receive the depth maps 512 and headposes 514, and anyother data from the sensors, and integrate that data into areconstruction 518. The reconstruction 518 may be more complete and lessnoisy than the sensor data. The world reconstruction component 516 mayupdate the reconstruction 518 using spatial and temporal averaging ofthe sensor data from multiple viewpoints over time.

The reconstruction 518 may include representations of the physical worldin one or more data formats including, for example, voxels, meshes,planes, etc. The different formats may represent alternativerepresentations of the same portions of the physical world or mayrepresent different portions of the physical world. In the illustratedexample, on the left side of the reconstruction 518, portions of thephysical world are presented as a global surface; on the right side ofthe reconstruction 518, portions of the physical world are presented asmeshes.

In some embodiments, the map maintained by headpose component 514 may besparse relative to other maps that might be maintained of the physicalworld. Rather than providing information about relative or absolutelocations, and possibly other characteristics, of surfaces, the sparsemap may indicate locations of interest points and/or structures, such ascorners or edges, instead of all the locations of features. In someembodiments, the map may include image frames as captured by the sensors522. These frames may be reduced to features, which may represent theinterest points and/or structures. In conjunction with each frame,information about a pose of a user from which the frame was acquired mayalso be stored as part of the map. In some embodiments, every imageacquired by the sensor may or may not be stored. In some embodiments,the system may process images as they are collected by sensors andselect subsets of the image frames for further computation. Theselection may be based on one or more criteria that limits the additionof information yet ensures that the map contains useful information. Thesystem may add a new image frame to the map, for example, based onoverlap with a prior image frame already added to the map or based onthe image frame containing a sufficient number of features determined aslikely to represent stationary objects. In some embodiments, theselected image frames, or groups of features from selected image framesmay serve as key frames for the map, which are used to provide spatialinformation.

In some embodiments, the amount of data that is processed whenconstructing maps may be reduced, such as by constructing sparse mapswith a collection of mapped points and keyframes and/or dividing themaps into blocks to enable updates by blocks. A mapped point may beassociated with a point of interest in the environment. A keyframe mayinclude selected information from camera-captured data. U.S. patentapplication Ser. No. 16/520,582 describes determining and/or evaluatinglocalization maps and is hereby incorporated herein by reference in itsentirety.

The AR system 502 may integrate sensor data over time from multipleviewpoints of a physical world. The poses of the sensors (e.g., positionand orientation) may be tracked as a device including the sensors ismoved. As the sensor's frame pose is known and how it relates to theother poses, each of these multiple viewpoints of the physical world maybe fused together into a single, combined reconstruction of the physicalworld, which may serve as an abstract layer for the map and providespatial information. The reconstruction may be more complete and lessnoisy than the original sensor data by using spatial and temporalaveraging (i.e., averaging data from multiple viewpoints over time), orany other suitable method.

In the illustrated embodiment in FIG. 3 , a map represents the portionof the physical world in which a user of a single, wearable device ispresent. In that scenario, headpose associated with frames in the mapmay be represented as a local headpose, indicating orientation relativeto an initial orientation for a single device at the start of a session.For example, the headpose may be tracked relative to an initial headposewhen the device was turned on or otherwise operated to scan anenvironment to build a representation of that environment.

In combination with content characterizing that portion of the physicalworld, the map may include metadata. The metadata, for example, mayindicate time of capture of the sensor information used to form the map.Metadata alternatively or additionally may indicate location of thesensors at the time of capture of information used to form the map.Location may be expressed directly, such as with information from a GPSchip, or indirectly, such as with a wireless (e.g., Wi-Fi) signatureindicating strength of signals received from one or more wireless accesspoints while the sensor data was being collected and/or withidentifiers, such as BSSIDs, of wireless access points to which the userdevice connected while the sensor data was collected.

The reconstruction 518 may be used for AR functions, such as producing asurface representation of the physical world for occlusion processing orphysics-based processing. This surface representation may change as theuser moves or objects in the physical world change. Aspects of thereconstruction 518 may be used, for example, by a component 520 thatproduces a changing global surface representation in world coordinates,which may be used by other components.

The AR content may be generated based on this information, such as by ARapplications 504. An AR application 504 may be a game program, forexample, that performs one or more functions based on information aboutthe physical world, such as visual occlusion, physics-basedinteractions, and environment reasoning. It may perform these functionsby querying data in different formats from the reconstruction 518produced by the world reconstruction component 516. In some embodiments,component 520 may be configured to output updates when a representationin a region of interest of the physical world changes. That region ofinterest, for example, may be set to approximate a portion of thephysical world in the vicinity of the user of the system, such as theportion within the view field of the user, or is projected(predicted/determined) to come within the view field of the user.

The AR applications 504 may use this information to generate and updatethe AR contents. The virtual portion of the AR contents may be presentedon the display 508 in combination with the see-through reality 510,creating a realistic user experience.

In some embodiments, an AR experience may be provided to a user throughan XR device, which may be a wearable display device, which may be partof a system that may include remote processing and or remote datastorage and/or, in some embodiments, other wearable display devices wornby other users. FIG. 4 illustrates an example of system 580 (hereinafterreferred to as “system 580”) including a single wearable device forsimplicity of illustration. The system 580 includes a head mounteddisplay device 562 (hereinafter referred to as “display device 562”),and various mechanical and electronic modules and systems to support thefunctioning of the display device 562. The display device 562 may becoupled to a frame 564, which is wearable by a display system user orviewer 560 (hereinafter referred to as “user 560”) and configured toposition the display device 562 in front of the eyes of the user 560.According to various embodiments, the display device 562 may be asequential display. The display device 562 may be monocular orbinocular. In some embodiments, the display device 562 may be an exampleof the display 508 in FIG. 3 .

In some embodiments, a speaker 566 is coupled to the frame 564 andpositioned proximate an ear canal of the user 560. In some embodiments,another speaker, not shown, is positioned adjacent another ear canal ofthe user 560 to provide for stereo/shapeable sound control. The displaydevice 562 is operatively coupled, such as by a wired lead or wirelessconnectivity 568, to a local data processing module 570 which may bemounted in a variety of configurations, such as fixedly attached to theframe 564, fixedly attached to a helmet or hat worn by the user 560,embedded in headphones, or otherwise removably attached to the user 560(e.g., in a backpack-style configuration, in a belt-coupling styleconfiguration).

The local data processing module 570 may include a processor, as well asdigital memory, such as non-volatile memory (e.g., flash memory), bothof which may be utilized to assist in the processing, caching, andstorage of data. The data include data a) captured from sensors (whichmay be, e.g., operatively coupled to the frame 564) or otherwiseattached to the user 560, such as image capture devices (such ascameras), microphones, inertial measurement units, accelerometers,compasses, GPS units, radio devices, and/or gyros; and/or b) acquiredand/or processed using remote processing module 572 and/or remote datarepository 574, possibly for passage to the display device 562 aftersuch processing or retrieval.

In some embodiments, the wearable deice may communicate with remotecomponents. The local data processing module 570 may be operativelycoupled by communication links 576, 578, such as via a wired or wirelesscommunication links, to the remote processing module 572 and remote datarepository 574, respectively, such that these remote modules 572, 574are operatively coupled to each other and available as resources to thelocal data processing module 570. In further embodiments, in addition oras alternative to remote data repository 574, the wearable device canaccess cloud based remote data repositories and/or services. In someembodiments, the head pose tracking component described above may be atleast partially implemented in the local data processing module 570. Insome embodiments, the world reconstruction component 516 in FIG. 3 maybe at least partially implemented in the local data processing module570. For example, the local data processing module 570 may be configuredto execute computer executable instructions to generate the map and/orthe physical world representations based at least in part on at least aportion of the data.

In some embodiments, processing may be distributed across local andremote processors. For example, local processing may be used toconstruct a map on a user device (e.g., tracking map) based on sensordata collected with sensors on that user's device. Such a map may beused by applications on that user's device. Additionally, previouslycreated maps (e.g., canonical maps) may be stored in remote datarepository 574. Where a suitable stored or persistent map is available,it may be used instead of or in addition to the tracking map createdlocally on the device. In some embodiments, a tracking map may belocalized to the stored map, such that a correspondence is establishedbetween a tracking map, which might be oriented relative to, forexample, a coordinate system with an origin at a fixed, known location,a relative coordinate system with an origin at the position of thewearable device at the time a user turned the system on, etc., and thecanonical map, which may be oriented relative to one or more persistentfeatures. In some embodiments, the persistent map might be loaded on theuser device to allow the user device to render virtual content without adelay associated with scanning a location to build a tracking map of theuser's full environment from sensor data acquired during the scan. Insome embodiments, the user device may access a remote persistent map(e.g., stored on a cloud) without the need to download the persistentmap on the user device.

In some embodiments, spatial information may be communicated from thewearable device to remote services, such as a cloud service that isconfigured to localize a device to stored maps maintained on the cloudservice. According to one embodiment, the localization processing cantake place in the cloud matching the device location to existing maps,such as canonical maps, and return transforms that link virtual contentto the wearable device location. In such embodiments, the system canavoid communicating maps from remote resources to the wearable device.Other embodiments can be configured for both device-based andcloud-based localization, for example, to enable functionality wherenetwork connectivity is not available or a user opts not to enablecould-based localization.

Alternatively, or additionally, the tracking map may be merged withpreviously stored maps to extend or improve the quality of those maps.The processing to determine whether a suitable previously createdenvironment map is available and/or to merge a tracking map with one ormore stored environment maps may be done in local data processing module570 or remote processing module 572.

In some embodiments, the local data processing module 570 may includeone or more processors (e.g., a graphics processing unit (GPU))configured to analyze and process data and/or image information. In someembodiments, the local data processing module 570 may include a singleprocessor (e.g., a single-core or multi-core ARM processor), which wouldlimit the local data processing module 570's compute budget but enable amore miniature device. In some embodiments, the world reconstructioncomponent 516 may use a compute budget less than a single Advanced RISCMachine (ARM) core to generate physical world representations inreal-time on a non-predefined space such that the remaining computebudget of the single ARM core can be accessed for other uses such as,for example, extracting meshes.

In some embodiments, the remote data repository 574 may include adigital data storage facility, which may be available through theInternet or other networking configuration in a “cloud” resourceconfiguration. In some embodiments, all data is stored and allcomputations are performed in the local data processing module 570,allowing fully autonomous use from a remote module. In some embodiments,all data is stored and all or most computations are performed in theremote data repository 574, allowing for a smaller device. A worldreconstruction, for example, may be stored in whole or in part in thisrepository 574.

In embodiments in which data is stored remotely, and accessible over anetwork, data may be shared by multiple users of an augmented realitysystem. For example, user devices may upload their tracking maps toaugment a database of environment maps. In some embodiments, thetracking map upload occurs at the end of a user session with a wearabledevice. In some embodiments, the tracking map uploads may occurcontinuously, semi-continuously, intermittently, at a pre-defined time,after a pre-defined period from the previous upload, or when triggeredby an event. A tracking map uploaded by any user device may be used toexpand or improve a previously stored map, whether based on data fromthat user device or any other user device. Likewise, a persistent mapdownloaded to a user device may be based on data from that user deviceor any other user device. In this way, high quality environment maps maybe readily available to users to improve their experiences with the ARsystem.

In further embodiments, persistent map downloads can be limited and/oravoided based on localization executed on remote resources (e.g., in thecloud). In such configurations, a wearable device or other XR devicecommunicates to the cloud service feature information coupled with poseinformation (e.g., positioning information for the device at the timethe features represented in the feature information were sensed). One ormore components of the cloud service may match the feature informationto respective stored maps (e.g., canonical maps) and generatestransforms between a tracking map maintained by the XR device and thecoordinate system of the canonical map. Each XR device that has itstracking map localized with respect to the canonical map may accuratelyrender virtual content in locations specified with respect to thecanonical map based on its own tracking.

In some embodiments, the local data processing module 570 is operativelycoupled to a battery 582. In some embodiments, the battery 582 is aremovable power source, such as over the counter batteries. In otherembodiments, the battery 582 is a lithium-ion battery. In someembodiments, the battery 582 includes both an internal lithium-ionbattery chargeable by the user 560 during non-operation times of thesystem 580 and removable batteries such that the user 560 may operatethe system 580 for longer periods of time without having to be tetheredto a power source to charge the lithium-ion battery or having to shutthe system 580 off to replace batteries.

FIG. 5A illustrates a user 530 wearing an AR display system rendering ARcontent as the user 530 moves through a physical world environment 532(hereinafter referred to as “environment 532”). The information capturedby the AR system along the movement path of the user may be processedinto one or more tracking maps. The user 530 positions the AR displaysystem at positions 534, and the AR display system records ambientinformation of a passable world (e.g., a digital representation of thereal objects in the physical world that can be stored and updated withchanges to the real objects in the physical world) relative to thepositions 534. That information may be stored as poses in combinationwith images, features, directional audio inputs, or other desired data.The positions 534 are aggregated to data inputs 536, for example, aspart of a tracking map, and processed at least by a passable worldmodule 538, which may be implemented, for example, by processing on aremote processing module 572 of FIG. 4 . In some embodiments, thepassable world module 538 may include the head pose component 514 andthe world reconstruction component 516, such that the processedinformation may indicate the location of objects in the physical worldin combination with other information about physical objects used inrendering virtual content.

The passable world module 538 determines, at least in part, where andhow AR content 540 can be placed in the physical world as determinedfrom the data inputs 536. The AR content is “placed” in the physicalworld by presenting via the user interface both a representation of thephysical world and the AR content, with the AR content rendered as if itwere interacting with objects in the physical world and the objects inthe physical world presented as if the AR content were, whenappropriate, obscuring the user's view of those objects. In someembodiments, the AR content may be placed by appropriately selectingportions of a fixed element 542 (e.g., a table) from a reconstruction(e.g., the reconstruction 518) to determine the shape and position ofthe AR content 540. As an example, the fixed element may be a table andthe virtual content may be positioned such that it appears to be on thattable. In some embodiments, the AR content may be placed withinstructures in a field of view 544, which may be a present field of viewor an estimated future field of view. In some embodiments, the ARcontent may be persisted relative to a model 546 of the physical world(e.g., a mesh).

As depicted, the fixed element 542 serves as a proxy (e.g., digitalcopy) for any fixed element within the physical world which may bestored in the passable world module 538 so that the user 530 canperceive content on the fixed element 542 without the system having tomap to the fixed element 542 each time the user 530 sees it. The fixedelement 542 may, therefore, be a mesh model from a previous modelingsession or determined from a separate user but nonetheless stored by thepassable world module 538 for future reference by a plurality of users.Therefore, the passable world module 538 may recognize the environment532 from a previously mapped environment and display AR content withouta device of the user 530 mapping all or part of the environment 532first, saving computation process and cycles and avoiding latency of anyrendered AR content.

The mesh model 546 of the physical world may be created by the ARdisplay system and appropriate surfaces and metrics for interacting anddisplaying the AR content 540 can be stored by the passable world module538 for future retrieval by the user 530 or other users without the needto completely or partially recreate the model. In some embodiments, thedata inputs 536 are inputs such as geo-location, user identification,and current activity to indicate to the passable world module 538 whichfixed element 542 of one or more fixed elements are available, which ARcontent 540 has last been placed on the fixed element 542, and whetherto display that same content (such AR content being “persistent” contentregardless of user viewing a particular passable world model).

Even in embodiments in which objects are considered to be fixed (e.g., akitchen table), the passable world module 538 may update those objectsin a model of the physical world from time to time to account for thepossibility of changes in the physical world. The model of fixed objectsmay be updated with a very low frequency. Other objects in the physicalworld may be moving or otherwise not regarded as fixed (e.g., kitchenchairs). To render an AR scene with a realistic feel, the AR system mayupdate the position of these non-fixed objects with a much higherfrequency than is used to update fixed objects. To enable accuratetracking of all of the objects in the physical world, an AR system maydraw information from multiple sensors, including one or more imagesensors.

FIG. 5B is a schematic illustration of a viewing optics assembly 548 andattendant components. In some embodiments, two eye tracking cameras 550,directed toward user eyes 549, detect metrics of the user eyes 549, suchas eye shape, eyelid occlusion, pupil direction and glint on the usereyes 549.

In some embodiments, one of the sensors may be a depth sensor 551, suchas a time-of-flight sensor, emitting signals to the world and detectingreflections of those signals from nearby objects to determine distanceto given objects. A depth sensor, for example, may quickly determinewhether objects have entered the field of view of the user, either as aresult of motion of those objects or a change of pose of the user.However, information about the position of objects in the field of viewof the user may alternatively or additionally be collected with othersensors. Depth information, for example, may be obtained fromstereoscopic visual image sensors or plenoptic sensors.

In some embodiments, world cameras 552 record a greater-than-peripheralview to map and/or otherwise create a model of the environment 532 anddetect inputs that may affect AR content. In some embodiments, the worldcamera 552 and/or camera 553 may be grayscale and/or color imagesensors, which may output grayscale and/or color image frames at fixedtime intervals. Camera 553 may further capture physical world imageswithin a field of view of the user at a specific time. Pixels of aframe-based image sensor may be sampled repetitively even if theirvalues are unchanged. Each of the world cameras 552, the camera 553 andthe depth sensor 551 have respective fields of view of 554, 555, and 556to collect data from and record a physical world scene, such as thephysical world environment 532 depicted in FIG. 34A.

Inertial measurement units 557 may determine movement and orientation ofthe viewing optics assembly 548. In some embodiments, each component isoperatively coupled to at least one other component. For example, thedepth sensor 551 is operatively coupled to the eye tracking cameras 550as a confirmation of measured accommodation against actual distance theuser eyes 549 are looking at.

It should be appreciated that a viewing optics assembly 548 may includesome of the components illustrated in FIG. 34B and may includecomponents instead of or in addition to the components illustrated. Insome embodiments, for example, a viewing optics assembly 548 may includetwo world camera 552 instead of four. Alternatively, or additionally,cameras 552 and 553 need not capture a visible light image of their fullfield of view. A viewing optics assembly 548 may include other types ofcomponents. In some embodiments, a viewing optics assembly 548 mayinclude one or more dynamic vision sensor (DVS), whose pixels mayrespond asynchronously to relative changes in light intensity exceedinga threshold.

In some embodiments, a viewing optics assembly 548 may not include thedepth sensor 551 based on time-of-flight information. In someembodiments, for example, a viewing optics assembly 548 may include oneor more plenoptic cameras, whose pixels may capture light intensity andan angle of the incoming light, from which depth information can bedetermined. For example, a plenoptic camera may include an image sensoroverlaid with a transmissive diffraction mask (TDM). Alternatively, oradditionally, a plenoptic camera may include an image sensor containingangle-sensitive pixels and/or phase-detection auto-focus pixels (PDAF)and/or micro-lens array (MLA). Such a sensor may serve as a source ofdepth information instead of or in addition to depth sensor 551.

It also should be appreciated that the configuration of the componentsin FIG. 5B is provided as an example. A viewing optics assembly 548 mayinclude components with any suitable configuration, which may be set toprovide the user with the largest field of view practical for aparticular set of components. For example, if a viewing optics assembly548 has one world camera 552, the world camera may be placed in a centerregion of the viewing optics assembly instead of at a side.

Information from the sensors in viewing optics assembly 548 may becoupled to one or more of processors in the system. The processors maygenerate data that may be rendered so as to cause the user to perceivevirtual content interacting with objects in the physical world. Thatrendering may be implemented in any suitable way, including generatingimage data that depicts both physical and virtual objects. In otherembodiments, physical and virtual content may be depicted in one sceneby modulating the opacity of a display device that a user looks throughat the physical world. The opacity may be controlled so as to create theappearance of the virtual object and also to block the user from seeingobjects in the physical world that are occluded by the virtual objects.In some embodiments, the image data may only include virtual contentthat may be modified such that the virtual content is perceived by auser as realistically interacting with the physical world (e.g., clipcontent to account for occlusions), when viewed through the userinterface.

The location on the viewing optics assembly 548 at which content isdisplayed to create the impression of an object at a particular locationmay depend on the physics of the viewing optics assembly. Additionally,the pose of the user's head with respect to the physical world and thedirection in which the user's eyes are looking may impact where in thephysical world content displayed at a particular location on the viewingoptics assembly content will appear. Sensors as described above maycollect this information, and or supply information from which thisinformation may be calculated, such that a processor receiving sensorinputs may compute where objects should be rendered on the viewingoptics assembly 548 to create a desired appearance for the user.

Regardless of how content is presented to a user, a model of thephysical world may be used so that characteristics of the virtualobjects, which can be impacted by physical objects, including the shape,position, motion, and visibility of the virtual object, can be correctlycomputed. In some embodiments, the model may include the reconstructionof a physical world, for example, the reconstruction 518.

That model may be created from data collected from sensors on a wearabledevice of the user. Though, in some embodiments, the model may becreated from data collected by multiple users, which may be aggregatedin a computing device remote from all of the users (and which may be “inthe cloud”).

The model may be created, at least in part, by a world reconstructionsystem such as, for example, the world reconstruction component 516 ofFIG. 3 depicted in more detail in FIG. 6A. The world reconstructioncomponent 516 may include a perception module 660 that may generate,update, and store representations for a portion of the physical world.In some embodiments, the perception module 660 may represent the portionof the physical world within a reconstruction range of the sensors asmultiple voxels. Each voxel may correspond to a 3D cube of apredetermined volume in the physical world, and include surfaceinformation, indicating whether there is a surface in the volumerepresented by the voxel. Voxels may be assigned values indicatingwhether their corresponding volumes have been determined to includesurfaces of physical objects, determined to be empty or have not yetbeen measured with a sensor and so their value is unknown. It should beappreciated that values indicating that voxels that are determined to beempty or unknown need not be explicitly stored, as the values of voxelsmay be stored in computer memory in any suitable way, including storingno information for voxels that are determined to be empty or unknown.

In addition to generating information for a persisted worldrepresentation, the perception module 660 may identify and outputindications of changes in a region around a user of an AR system.Indications of such changes may trigger updates to volumetric datastored as part of the persisted world, or trigger other functions, suchas triggering components 604 that generate AR content to update the ARcontent.

In some embodiments, the perception module 660 may identify changesbased on a signed distance function (SDF) model. The perception module660 may be configured to receive sensor data such as, for example, depthmaps 660 a and headposes 660 b, and then fuse the sensor data into a SDFmodel 660 c. Depth maps 660 a may provide SDF information directly, andimages may be processed to arrive at SDF information. The SDFinformation represents distance from the sensors used to capture thatinformation. As those sensors may be part of a wearable unit, the SDFinformation may represent the physical world from the perspective of thewearable unit and therefore the perspective of the user. The headposes660 b may enable the SDF information to be related to a voxel in thephysical world.

In some embodiments, the perception module 660 may generate, update, andstore representations for the portion of the physical world that iswithin a perception range. The perception range may be determined based,at least in part, on a sensor's reconstruction range, which may bedetermined based, at least in part, on the limits of a sensor'sobservation range. As a specific example, an active depth sensor thatoperates using active IR pulses may operate reliably over a range ofdistances, creating the observation range of the sensor, which may befrom a few centimeters or tens of centimeters to a few meters.

The world reconstruction component 516 may include additional modulesthat may interact with the perception module 660. In some embodiments, apersisted world module 662 may receive representations for the physicalworld based on data acquired by the perception module 660. The persistedworld module 662 also may include various formats of representations ofthe physical world. For example, volumetric metadata 662 b such asvoxels may be stored as well as meshes 662 c and planes 662 d. In someembodiments, other information, such as depth maps could be saved.

In some embodiments, representations of the physical world, such asthose illustrated in FIG. 6A may provide relatively dense informationabout the physical world in comparison to sparse maps, such as atracking map based on feature points as described above.

In some embodiments, the perception module 660 may include modules thatgenerate representations for the physical world in various formatsincluding, for example, meshes 660 d, planes and semantics 660 e. Therepresentations for the physical world may be stored across local andremote storage mediums. The representations for the physical world maybe described in different coordinate frames depending on, for example,the location of the storage medium. For example, a representation forthe physical world stored in the device may be described in a coordinateframe local to the device. The representation for the physical world mayhave a counterpart stored in a cloud. The counterpart in the cloud maybe described in a coordinate frame shared by all devices in an XRsystem.

In some embodiments, these modules may generate representations based ondata within the perception range of one or more sensors at the time therepresentation is generated as well as data captured at prior times andinformation in the persisted world module 662. In some embodiments,these components may operate on depth information captured with a depthsensor. However, the AR system may include vision sensors and maygenerate such representations by analyzing monocular or binocular visioninformation.

In some embodiments, these modules may operate on regions of thephysical world. Those modules may be triggered to update a subregion ofthe physical world, when the perception module 660 detects a change inthe physical world in that subregion. Such a change, for example, may bedetected by detecting a new surface in the SDF model 660 c or othercriteria, such as changing the value of a sufficient number of voxelsrepresenting the subregion.

The world reconstruction component 516 may include components 664 thatmay receive representations of the physical world from the perceptionmodule 660. Information about the physical world may be pulled by thesecomponents according to, for example, a use request from an application.In some embodiments, information may be pushed to the use components,such as via an indication of a change in a pre-identified region or achange of the physical world representation within the perception range.The components 664, may include, for example, game programs and othercomponents that perform processing for visual occlusion, physics-basedinteractions, and environment reasoning.

Responding to the queries from the components 664, the perception module660 may send representations for the physical world in one or moreformats. For example, when the component 664 indicates that the use isfor visual occlusion or physics-based interactions, the perceptionmodule 660 may send a representation of surfaces. When the component 664indicates that the use is for environmental reasoning, the perceptionmodule 660 may send meshes, planes and semantics of the physical world.

In some embodiments, the perception module 660 may include componentsthat format information to provide the component 664. An example of sucha component may be raycasting component 660 f. A use component (e.g.,component 664), for example, may query for information about thephysical world from a particular point of view. Raycasting component 660f may select from one or more representations of the physical world datawithin a field of view from that point of view.

As should be appreciated from the foregoing description, the perceptionmodule 660, or another component of an AR system, may process data tocreate 3D representations of portions of the physical world. Data to beprocessed may be reduced by culling parts of a 3D reconstruction volumebased at last in part on a camera frustum and/or depth image, extractingand persisting plane data, capturing, persisting, and updating 3Dreconstruction data in blocks that allow local update while maintainingneighbor consistency, providing occlusion data to applicationsgenerating such scenes, where the occlusion data is derived from acombination of one or more depth data sources, and/or performing amulti-stage mesh simplification. The reconstruction may contain data ofdifferent levels of sophistication including, for example, raw data suchas live depth data, fused volumetric data such as voxels, and computeddata such as meshes.

In some embodiments, components of a passable world model may bedistributed, with some portions executing locally on an XR device andsome portions executing remotely, such as on a network connected server,or otherwise in the cloud. The allocation of the processing and storageof information between the local XR device and the cloud may impactfunctionality and user experience of an XR system. For example, reducingprocessing on a local device by allocating processing to the cloud mayenable longer battery life and reduce heat generated on the localdevice. But, allocating too much processing to the cloud may createundesirable latency that causes an unacceptable user experience.

FIG. 6B depicts a distributed component architecture 600 configured forspatial computing, according to some embodiments. The distributedcomponent architecture 600 may include a passable world component 602(e.g., PW 538 in FIG. 5A), a Lumin OS 604, API's 606, SDK 608, andApplication 610. The Lumin OS 604 may include a Linux-based kernel withcustom drivers compatible with an XR device. The API's 606 may includeapplication programming interfaces that grant XR applications (e.g.,Applications 610) access to the spatial computing features of an XRdevice. The SDK 608 may include a software development kit that allowsthe creation of XR applications.

One or more components in the architecture 600 may create and maintain amodel of a passable world. In this example sensor data is collected on alocal device. Processing of that sensor data may be performed in partlocally on the XR device and partially in the cloud. PW 538 may includeenvironment maps created based, at least in part, on data captured by ARdevices worn by multiple users. During sessions of an AR experience,individual AR devices (such as wearable devices described above inconnection with FIG. 4 may create tracking maps, which is one type ofmap.

In some embodiments, the device may include components that constructboth sparse maps and dense maps. A tracking map may serve as a sparsemap and may include headposes of the AR device scanning an environmentas well as information about objects detected within that environment ateach headpose. Those headposes may be maintained locally for eachdevice. For example, the headpose on each device may be relative to aninitial headpose when the device was turned on for its session. As aresult, each tracking map may be local to the device creating it. Thedense map may include surface information, which may be represented by amesh or depth information. Alternatively, or additionally, a dense mapmay include higher level information derived from surface or depthinformation, such as the location and/or characteristics of planesand/or other objects.

Creation of the dense maps may be independent of the creation of sparsemaps, in some embodiments. The creation of dense maps and sparse maps,for example, may be performed in separate processing pipelines within anAR system. Separating processing, for example, may enable generation orprocessing of different types of maps to be performed at differentrates. Sparse maps, for example, may be refreshed at a faster rate thandense maps. In some embodiments, however, the processing of dense andsparse maps may be related, even if performed in different pipelines.Changes in the physical world revealed in a sparse map, for example, maytrigger updates of a dense map, or vice versa. Further, even ifindependently created, the maps might be used together. For example, acoordinate system derived from a sparse map may be used to defineposition and/or orientation of objects in a dense map.

The sparse map and/or dense map may be persisted for re-use by the samedevice and/or sharing with other devices. Such persistence may beachieved by storing information in the cloud. The AR device may send thetracking map to a cloud to, for example, merge with environment mapsselected from persisted maps previously stored in the cloud. In someembodiments, the selected persisted maps may be sent from the cloud tothe AR device for merging. In some embodiments, the persisted maps maybe oriented with respect to one or more persistent coordinate frames.Such maps may serve as canonical maps, as they can be used by any ofmultiple devices. In these embodiments, a canonical map includes a mapof any kind that is oriented or positioned with respect to a referenceorientation or a reference coordinate system (e.g., an absolutecoordinate system referencing a fixed, known location as the origin, arelative coordinate system referencing a relative location such as aportable computing device generating the map, etc.) and may thus be usedby any of multiple computing devices at their respective, differentgeographic locations as a computing device of these multiple computingdevices may resolve the reference orientation or reference coordinatesystem and determine where various features in the map are locatedrelative to the computing device. In some embodiments, a model of apassable world may comprise or be created from one or more canonicalmaps. Devices, even though they perform some operations based on acoordinate frame local to the device, may nonetheless use the canonicalmap by determining a transformation between their coordinate frame localto the device and the canonical map.

A canonical map may originate as a tracking map (TM) (e.g., TM 1102 inFIG. 31A), which may be promoted to a canonical map. The canonical mapmay be persisted such that devices that access the canonical map may,once determining a transformation between their respective localcoordinate systems of the devices and a coordinate system of thecanonical map, use the information in the canonical map to determinelocations of objects represented in the canonical map in the physicalworld around the device. In some embodiments, a TM may be a headposesparse map created by an XR device. In some embodiments, the canonicalmap may be created when an XR device sends one or more TMs to a cloudserver for merging with additional TMs captured by the XR device at adifferent time or by other XR devices.

The canonical maps, or other maps, may provide information about theportions of the physical world represented by the data processed tocreate respective maps. FIG. 7 depicts an exemplary tracking map 700,according to some embodiments. The tracking map 700 may provide a floorplan 706 of physical objects in a corresponding physical world,represented by points or point nodes 702. In some embodiments, a mappoint or map point node 702 may represent a feature of a physical objectthat may include multiple features. For example, each corner of a tablemay be a feature that is represented by a point on a map. The featuresmay be derived from processing images, such as may be acquired with thesensors of a wearable device in an augmented reality system. Thefeatures, for example, may be derived by processing an image frameoutput by a sensor to identify features based on large gradients (e.g.,a gradient value exceeding a threshold value) in the image or othersuitable criteria. Further processing may limit the number of featuresin each frame. For example, processing may select features that likelyrepresent persistent objects. One or more heuristics may be applied forthis selection.

The tracking map 700 may include data on points 702 collected by adevice. For each image frame with data points included in a trackingmap, a pose may be stored. The pose may represent the orientation fromwhich the image frame was captured, such that the feature points withineach image frame may be spatially correlated. The pose may be determinedby positioning information, such as may be derived from the sensors,such as an IMU sensor, on the wearable device. Alternatively, oradditionally, the pose may be determined from matching image frames toother image frames that depict overlapping portions of the physicalworld. By finding such positional correlation, which may be accomplishedby matching subsets of features points in two frames, the relative posebetween the two frames may be computed. A relative pose may be adequatefor a tracking map, as the map may be relative to a coordinate systemlocal to a device (or a global coordinate system based on a fixed, knownorigin) established based on the initial pose of the device whenconstruction of the tracking map was initiated.

Not all of the feature points and image frames collected by a device maybe retained as part of the tracking map, as much of the informationcollected with the sensors is likely to be redundant. Rather, onlycertain frames may be added to the map. Those frames may be selectedbased on one or more criteria, such as degree of overlap with imageframes already in the map, the number of new features they contain or aquality metric for the features in the frame. Image frames not added tothe tracking map may be discarded or may be used to revise the locationof features. As a further alternative, all or most of the image frames,represented as a set of features may be retained, but a subset of thoseframes may be designated as key frames, which are used for furtherprocessing.

The key frames may be processed to produce keyrigs 704. The key framesmay be processed to produce three dimensional sets of feature points andsaved as keyrigs 704. Such processing may entail, for example, comparingimage frames derived simultaneously from two cameras to stereoscopicallydetermine the 3D position of feature points. Metadata may be associatedwith these keyframes and/or keyrigs, such as poses.

The environment maps may have any of multiple formats depending on, forexample, the storage locations of an environment map including, forexample, local storage of AR devices and remote storage. For example, amap in remote storage may have higher resolution than a map in localstorage on a wearable device where memory is limited. To send a higherresolution map from remote storage to local storage, the map may be downsampled or otherwise converted to an appropriate format, such as byreducing the number of poses per area of the physical world stored inthe map and/or the number of feature points stored for each pose. Insome embodiments, a slice or portion of a high-resolution map fromremote storage may be sent to local storage, where the slice or portionis not down sampled.

A database of environment maps may be updated as new tracking maps arecreated. To determine which of a potentially very large number ofenvironment maps in a database is to be updated, updating may includeefficiently selecting one or more environment maps stored in thedatabase relevant to the new tracking map. The selected one or moreenvironment maps may be ranked by relevance and one or more of thehigher or highest ranked maps may be selected for processing to mergehigher ranked selected environment maps with the new tracking map tocreate one or more updated environment maps. When a new tracking maprepresents a portion of the physical world for which there is nopreexisting environment map to update, that tracking map may be storedin the database as a new environment map.

View Independent Display

Described herein are methods and apparatus for providing virtualcontents using an XR system, independent of locations of eyes viewingthe virtual content. Conventionally, a virtual content is re-renderedupon any motion of the displaying system. For example, if a user wearinga display system views a virtual representation of a three-dimensional(3D) object on the display and walks around the area where the 3D objectappears, the 3D object should be re-rendered for each viewpoint suchthat the user has the perception that he or she is walking around anobject that occupies real space. However, the re-rendering consumessignificant computational resources of a system and causes artifacts dueto latency.

The inventors have recognized and appreciated that head pose (e.g., thelocation and orientation of a user wearing an XR system) may be used torender a virtual content independent of eye rotations within a head ofthe user. In some embodiments, dynamic maps of a scene may be generatedbased on multiple coordinate frames in real space across one or moresessions such that virtual contents interacting with the dynamic mapsmay be rendered robustly, independent of eye rotations within the headof the user and/or independent of sensor deformations caused by, forexample, heat generated during high-speed, computation-intensiveoperation. In some embodiments, the configuration of multiple coordinateframes may enable a first XR device worn by a first user and a second XRdevice worn by a second user to recognize a common location in a scene.In some embodiments, the configuration of multiple coordinate frames mayenable users wearing XR devices to view a virtual content in a samelocation of a scene.

In some embodiments, a tracking map may be built in a world coordinateframe, which may have a world origin having a known location (e.g.,geographic location) and/or pose. The world origin may be the first poseof an XR device when the XR device is powered on. The world origin maybe aligned to gravity such that a developer of an XR application can getgravity alignment without extra work. Different tracking maps may bebuilt in different world coordinate frames because the tracking maps maybe captured by a same XR device at different sessions and/or differentXR devices worn by different users. In some embodiments, a session of anXR device may span from powering on to powering off the device. In someembodiments, an XR device may have a head coordinate frame, which mayhave a head origin. The head origin may be the current pose of an XRdevice when an image is taken. The difference between a head pose of aworld coordinate frame and a head pose of a head coordinate frame may beused to estimate a tracking route.

In some embodiments, an XR device may have a camera coordinate frame,which may have a camera origin. The camera origin may be the currentpose of one or more sensors of an XR device. The inventors haverecognized and appreciated that the configuration of a camera coordinateframe enables robust displaying virtual contents independent of eyerotation within a head of a user. This configuration also enables robustdisplaying of virtual contents independent of sensor deformation due to,for example, heat generated during operation.

In some embodiments, an XR device may have a head unit with ahead-mountable frame that a user can secure to their head and mayinclude two waveguides, one in front of each eye of the user. Thewaveguides may be transparent so that ambient light from real-worldobjects can transmit through the waveguides and the user can see thereal-world objects. Each waveguide may transmit projected light from aprojector to a respective eye of the user. The projected light may forman image on the retina of the eye. The retina of the eye thus receivesthe ambient light and the projected light. The user may simultaneouslysee real-world objects and one or more virtual objects that are createdby the projected light. In some embodiments, XR devices may have sensorsthat detect real-world objects around a user. These sensors may, forexample, be cameras that capture images that may be processed toidentify the locations of real-world objects.

In some embodiments, an XR system may assign a coordinate frame to avirtual content, as opposed to attaching the virtual content in a worldcoordinate frame. Such configuration enables a virtual content to bedescribed without regard to where it is rendered for a user, but it maybe attached to a more persistent frame position such as a persistentcoordinate frame (PCF) described in relation to, for example, FIGS.14-20C, to be rendered in a specified location. When the locations ofthe objects change, the XR device may detect the changes in theenvironment map and determine movement of the head unit worn by the userrelative to real-world objects.

FIG. 8 illustrates a user experiencing virtual content, as rendered byan XR system 10, in a physical environment, according to someembodiments. The XR system may include a first XR device 12.1 that isworn by a first user 14.1, a network 18 and a server 20. The user 14.1is in a physical environment with a real object in the form of a table16.

In the illustrated example, the first XR device 12.1 includes a headunit 22, a belt pack 24 and a cable connection 26. The first user 14.1secures the head unit 22 to their head and the belt pack 24 remotelyfrom the head unit 22 on their waist. The cable connection 26 connectsthe head unit 22 to the belt pack 24. The head unit 22 includestechnologies that are used to display a virtual object or objects to thefirst user 14.1 while the first user 14.1 is permitted to see realobjects such as the table 16. The belt pack 24 includes primarilyprocessing and communications capabilities of the first XR device 12.1.In some embodiments, the processing and communication capabilities mayreside entirely or partially in the head unit 22 such that the belt pack24 may be removed or may be located in another device such as abackpack.

In the illustrated example, the belt pack 24 is connected via a wirelessconnection to the network 18. The server 20 is connected to the network18 and holds data representative of local content. The belt pack 24downloads the data representing the local content from the server 20 viathe network 18. The belt pack 24 provides the data via the cableconnection 26 to the head unit 22. The head unit 22 may include adisplay that has a light source, for example, a laser light source or alight emitting diode (LED), and a waveguide that guides the light.

In some embodiments, the first user 14.1 may mount the head unit 22 totheir head and the belt pack 24 to their waist. The belt pack 24 maydownload image data representing virtual content over the network 18from the server 20. The first user 14.1 may see the table 16 through adisplay of the head unit 22. A projector forming part of the head unit22 may receive the image data from the belt pack 24 and generate lightbased on the image data. The light may travel through one or more of thewaveguides forming part of the display of the head unit 22. The lightmay then leave the waveguide and propagates onto a retina of an eye ofthe first user 14.1. The projector may generate the light in a patternthat is replicated on a retina of the eye of the first user 14.1. Thelight that falls on the retina of the eye of the first user 14.1 mayhave a selected field of depth so that the first user 14.1 perceives animage at a preselected depth behind the waveguide. In addition, botheyes of the first user 14.1 may receive slightly different images sothat a brain of the first user 14.1 perceives a three-dimensional imageor images at selected distances from the head unit 22. In theillustrated example, the first user 14.1 perceives a virtual content 28above the table 16. The proportions of the virtual content 28 and itslocation and distance from the first user 14.1 are determined by thedata representing the virtual content 28 and various coordinate framesthat are used to display the virtual content 28 to the first user 14.1.

In the illustrated example, the virtual content 28 is not visible fromthe perspective of the drawing and is visible to the first user 14.1through using the first XR device 12.1. The virtual content 28 mayinitially reside as data structures within vision data and algorithms inthe belt pack 24. The data structures may then manifest themselves aslight when the projectors of the head unit 22 generate light based onthe data structures. It should be appreciated that although the virtualcontent 28 has no existence in three-dimensional space in front of thefirst user 14.1, the virtual content 28 is still represented in FIG. 1in three-dimensional space for illustration of what a wearer of headunit 22 perceives. The visualization of computer data inthree-dimensional space may be used in this description to illustratehow the data structures that facilitate the renderings are perceived byone or more users relate to one another within the data structures inthe belt pack 24.

FIG. 9 illustrates components of the first XR device 12.1, according tosome embodiments. The first XR device 12.1 may include the head unit 22,and various components forming part of the vision data and algorithmsincluding, for example, a rendering engine 30, various coordinatesystems 32, various origin and destination coordinate frames 34, andvarious origin to destination coordinate frame transformers 36. Thevarious coordinate systems may be based on intrinsics of to the XRdevice or may be determined by reference to other information, such as apersistent pose or a persistent coordinate system, as described herein.

The head unit 22 may include a head-mountable frame 40, a display system42, a real object detection camera 44, a movement tracking camera 46,and an inertial measurement unit 48.

The head-mountable frame 40 may have a shape that is securable to thehead of the first user 14.1 in FIG. 8 . The display system 42, realobject detection camera 44, movement tracking camera 46, and inertialmeasurement unit 48 may be mounted to the head-mountable frame 40 andtherefore move together with the head-mountable frame 40.

The coordinate systems 32 may include a local data system 52, a worldframe system 54, a head frame system 56, and a camera frame system 58.

The local data system 52 may include a data channel 62, a local framedetermining routine 64 and a local frame storing instruction 66. Thedata channel 62 may be an internal software routine, a hardwarecomponent such as an external cable or a radio frequency receiver, or ahybrid component such as a port that is opened up. The data channel 62may be configured to receive image data 68 representing a virtualcontent.

The local frame determining routine 64 may be connected to the datachannel 62. The local frame determining routine 64 may be configured todetermine a local coordinate frame 70. In some embodiments, the localframe determining routine may determine the local coordinate frame basedon real world objects or real-world locations. In some embodiments, thelocal coordinate frame may be based on a top edge relative to a bottomedge of a browser window, head or feet of a character, a node on anouter surface of a prism or bounding box that encloses the virtualcontent, or any other suitable location to place a coordinate frame thatdefines a facing direction of a virtual content and a location (e.g., anode, such as a placement node or PCF node) with which to place thevirtual content, etc.

The local frame storing instruction 66 may be connected to the localframe determining routine 64. One skilled in the art will understandthat software modules and routines are “connected” to one anotherthrough subroutines, calls, etc. The local frame storing instruction 66may store the local coordinate frame 70 as a local coordinate frame 72within the origin and destination coordinate frames 34. In someembodiments, the origin and destination coordinate frames 34 may be oneor more coordinate frames that may be manipulated or transformed inorder for a virtual content to persist between sessions. In someembodiments, a session may be the period of time between a boot-up andshut-down of an XR device. Two sessions may be two start-up andshut-down periods for a single XR device, or may be a start-up andshut-down for two different XR devices.

In some embodiments, the origin and destination coordinate frames 34 maybe the coordinate frames involved in one or more transformationsrequired in order for a first user's XR device and a second user's XRdevice to recognize a common location. In some embodiments, thedestination coordinate frame may be the output of a series ofcomputations and transformations applied to the target coordinate framein order for a first and second user to view a virtual content in thesame location.

The rendering engine 30 may be connected to the data channel 62. Therendering engine 30 may receive the image data 68 from the data channel62 such that the rendering engine 30 may render virtual content based,at least in part, on the image data 68.

The display system 42 may be connected to the rendering engine 30. Thedisplay system 42 may include components that transform the image data68 into visible light. The visible light may form two patterns, one foreach eye. The visible light may enter eyes of the first user 14.1 inFIG. 8 and may be detected on retinas of the eyes of the first user14.1.

The real object detection camera 44 may include one or more cameras thatmay capture images from different sides of the head-mountable frame 40.The movement tracking camera 46 may include one or more cameras thatcapture images on sides of the head-mountable frame 40. One set of oneor more cameras may be used instead of the two sets of one or morecameras representing the real object detection camera(s) 44 and themovement tracking camera(s) 46. In some embodiments, the cameras 44, 46may capture images. As described above these cameras may collect datathat is used to construct a tracking map.

The inertial measurement unit 48 may include a number of devices thatare used to detect movement of the head unit 22. The inertialmeasurement unit 48 may include a gravitation sensor, one or moreaccelerometers and one or more gyroscopes. The sensors of the inertialmeasurement unit 48, in combination, track movement of the head unit 22in at least three orthogonal directions and about at least threeorthogonal axes.

In the illustrated example, the world frame system 54 includes a worldsurface determining routine 78, a world frame determining routine 80,and a world frame storing instruction 82. The world surface determiningroutine 78 is connected to the real object detection camera 44. Theworld surface determining routine 78 receives images and/or key framesbased on the images that are captured by the real object detectioncamera 44 and processes the images to identify surfaces in the images. Adepth sensor (not shown) may determine distances to the surfaces. Thesurfaces are thus represented by data in three dimensions includingtheir sizes, shapes, and distances from the real object detectioncamera.

In some embodiments, a world coordinate frame 84 may be based on theorigin at the initialization of the head pose session. In someembodiments, the world coordinate frame may be located where the devicewas booted up, or could be somewhere new if head pose was lost duringthe boot session. In some embodiments, the world coordinate frame may bethe origin at the start of a head pose session.

In the illustrated example, the world frame determining routine 80 isconnected to the world surface determining routine 78 and determines aworld coordinate frame 84 based on the locations of the surfaces asdetermined by the world surface determining routine 78. The world framestoring instruction 82 is connected to the world frame determiningroutine 80 to receive the world coordinate frame 84 from the world framedetermining routine 80. The world frame storing instruction 82 storesthe world coordinate frame 84 as a world coordinate frame 86 within theorigin and destination coordinate frames 34.

The head frame system 56 may include a head frame determining routine 90and a head frame storing instruction 92. The head frame determiningroutine 90 may be connected to the movement tracking camera 46 and theinertial measurement unit 48. The head frame determining routine 90 mayuse data from the movement tracking camera 46 and the inertialmeasurement unit 48 to calculate a head coordinate frame 94. Forexample, the inertial measurement unit 48 may have a gravitation sensorthat determines the direction of gravitational force relative to thehead unit 22. The movement tracking camera 46 may continually captureimages that are used by the head frame determining routine 90 to refinethe head coordinate frame 94. The head unit 22 moves when the first user14.1 in FIG. 8 moves their head. The movement tracking camera 46 and theinertial measurement unit 48 may continuously provide data to the headframe determining routine 90 so that the head frame determining routine90 can update the head coordinate frame 94.

The head frame storing instruction 92 may be connected to the head framedetermining routine 90 to receive the head coordinate frame 94 from thehead frame determining routine 90. The head frame storing instruction 92may store the head coordinate frame 94 as a head coordinate frame 96among the origin and destination coordinate frames 34. The head framestoring instruction 92 may repeatedly store the updated head coordinateframe 94 as the head coordinate frame 96 when the head frame determiningroutine 90 recalculates the head coordinate frame 94. In someembodiments, the head coordinate frame may be the location of thewearable XR device 12.1 relative to the local coordinate frame 72.

The camera frame system 58 may include camera intrinsics 98. The cameraintrinsics 98 may include dimensions of the head unit 22 that arefeatures of its design and manufacture. The camera intrinsics 98 may beused to calculate a camera coordinate frame 100 that is stored withinthe origin and destination coordinate frames 34.

In some embodiments, the camera coordinate frame 100 may include allpupil positions of a left eye of the first user 14.1 in FIG. 8 . Whenthe left eye moves from left to right or up and down, the pupilpositions of the left eye are located within the camera coordinate frame100. In addition, the pupil positions of a right eye are located withina camera coordinate frame 100 for the right eye. In some embodiments,the camera coordinate frame 100 may include the location of the camerarelative to the local coordinate frame when an image is taken.

The origin to destination coordinate frame transformers 36 may include alocal-to-world coordinate transformer 104, a world-to-head coordinatetransformer 106, and a head-to-camera coordinate transformer 108. Thelocal-to-world coordinate transformer 104 may receive the localcoordinate frame 72 and transform the local coordinate frame 72 to theworld coordinate frame 86. The transformation of the local coordinateframe 72 to the world coordinate frame 86 may be represented as a localcoordinate frame transformed to world coordinate frame 110 within theworld coordinate frame 86.

The world-to-head coordinate transformer 106 may transform from theworld coordinate frame 86 to the head coordinate frame 96. Theworld-to-head coordinate transformer 106 may transform the localcoordinate frame transformed to world coordinate frame 110 to the headcoordinate frame 96. The transformation may be represented as a localcoordinate frame transformed to head coordinate frame 112 within thehead coordinate frame 96.

The head-to-camera coordinate transformer 108 may transform from thehead coordinate frame 96 to the camera coordinate frame 100. Thehead-to-camera coordinate transformer 108 may transform the localcoordinate frame transformed to head coordinate frame 112 to a localcoordinate frame transformed to camera coordinate frame 114 within thecamera coordinate frame 100. The local coordinate frame transformed tocamera coordinate frame 114 may be entered into the rendering engine 30.The rendering engine 30 may render the image data 68 representing thelocal content 28 based on the local coordinate frame transformed tocamera coordinate frame 114.

FIG. 10 is a spatial representation of the various origin anddestination coordinate frames 34. The local coordinate frame 72, worldcoordinate frame 86, head coordinate frame 96, and camera coordinateframe 100 are represented in the figure. In some embodiments, the localcoordinate frame associated with the XR content 28 may have a positionand rotation (e.g., may provide a node and facing direction) relative toa local and/or world coordinate frame and/or PCF when the virtualcontent is placed in the real world so the virtual content may be viewedby the user. Each camera may have its own camera coordinate frame 100encompassing all pupil positions of one eye. Reference numerals 104A and106A represent the transformations that are made by the local-to-worldcoordinate transformer 104, world-to-head coordinate transformer 106,and head-to-camera coordinate transformer 108 in FIG. 9 , respectively.

FIG. 11 depicts a camera render protocol for transforming from a headcoordinate frame to a camera coordinate frame, according to someembodiments. In the illustrated example, a pupil for a single eye movesfrom position A to B. A virtual object that is meant to appearstationary will project onto a depth plane at one of the two positions Aor B depending on the position of the pupil (assuming that the camera isconfigured to use a pupil-based coordinate frame). As a result, using apupil coordinate frame transformed to a head coordinate frame will causejitter in a stationary virtual object as the eye moves from position Ato position B. This situation is referred to as view dependent displayor projection.

As depicted in FIG. 12 , a camera coordinate frame (e.g., CR) ispositioned and encompasses all pupil positions and object projectionwill now be consistent regardless of pupil positions A and B. The headcoordinate frame transforms to the CR frame, which is referred to asview independent display or projection. An image reprojection may beapplied to the virtual content to account for a change in eye position,however, as the rendering is still in the same position, jitter isminimized.

FIG. 13 illustrates the display system 42 in more detail. The displaysystem 42 includes a stereoscopic analyzer 144 that is connected to therendering engine 30 and forms part of the vision data and algorithms.

The display system 42 further includes left and right projectors 166Aand 166B and left and right waveguides 170A and 170B. The left and rightprojectors 166A and 166B are connected to power supplies. Each projector166A and 166B has a respective input for image data to be provided tothe respective projector 166A or 166B. The respective projector 166A or166B, when powered, generates light in two-dimensional patterns andemanates the light therefrom. The left and right waveguides 170A and170B are positioned to receive light from the left and right projectors166A and 166B, respectively. The left and right waveguides 170A and 170Bare transparent waveguides.

In use, a user mounts the head mountable frame 40 to their head.Components of the head mountable frame 40 may, for example, include astrap (not shown) that wraps around the back of the head of the user.The left and right waveguides 170A and 170B are then located in front ofleft and right eyes 220A and 220B of the user.

The rendering engine 30 enters the image data that it receives into thestereoscopic analyzer 144. The image data is three-dimensional imagedata of the local content 28 in FIG. 8 . The image data is projectedonto a plurality of virtual planes. The stereoscopic analyzer 144analyzes the image data to determine left and right image data setsbased on the image data for projection onto each depth plane. The leftand right image data sets are data sets that represent two-dimensionalimages that are projected in three-dimensions to give the user aperception of a depth.

The stereoscopic analyzer 144 enters the left and right image data setsinto the left and right projectors 166A and 1668. The left and rightprojectors 166A and 166B then create left and right light patterns. Thecomponents of the display system 42 are shown in plain view, although itshould be understood that the left and right patterns aretwo-dimensional patterns when shown in front elevation view. Each lightpattern includes a plurality of pixels. For purposes of illustration,light rays 224A and 226A from two of the pixels are shown leaving theleft projector 166A and entering the left waveguide 170A. The light rays224A and 226A reflect from sides of the left waveguide 170A. It is shownthat the light rays 224A and 226A propagate through internal reflectionfrom left to right within the left waveguide 170A, although it should beunderstood that the light rays 224A and 226A also propagate in adirection into the paper using refractory and reflective systems.

The light rays 224A and 226A exit the left light waveguide 170A througha pupil 228A and then enter a left eye 220A through a pupil 230A of theleft eye 220A. The light rays 224A and 226A then fall on a retina 232Aof the left eye 220A. In this manner, the left light pattern falls onthe retina 232A of the left eye 220A. The user is given the perceptionthat the pixels that are formed on the retina 232A are pixels 234A and236A that the user perceives to be at some distance on a side of theleft waveguide 170A opposing the left eye 220A. Depth perception iscreated by manipulating the focal length of the light.

In a similar manner, the stereoscopic analyzer 144 enters the rightimage data set into the right projector 1668. The right projector 1668transmits the right light pattern, which is represented by pixels in theform of light rays 224B and 226B. The light rays 224B and 226B reflectwithin the right waveguide 1708 and exit through a pupil 228B. The lightrays 224B and 226B then enter through a pupil 230B of the right eye 220Band fall on a retina 232B of a right eye 220B. The pixels of the lightrays 224B and 226B are perceived as pixels 134B and 236B behind theright waveguide 170B.

The patterns that are created on the retinas 232A and 232B areindividually perceived as left and right images. The left and rightimages differ slightly from one another due to the functioning of thestereoscopic analyzer 144. The left and right images are perceived in amind of the user as a three-dimensional rendering.

As mentioned, the left and right waveguides 170A and 170B aretransparent. Light from a real-life object such as the table 16 on aside of the left and right waveguides 170A and 170B opposing the eyes220A and 220B can project through the left and right waveguides 170A and170B and fall on the retinas 232A and 232B.

Persistent Coordinate Frame (PCF)

Described herein are methods and apparatus for providing spatialpersistence across user instances within a shared space. Without spatialpersistence, virtual content placed in the physical world by a user in asession may not exist or may be misplaced in the user's view in adifferent session. Without spatial persistence, virtual content placedin the physical world by one user may not exist or may be out of placein a second user's view, even if the second user is intended to besharing an experience of the same physical space with the first user.

The inventors have recognized and appreciated that spatial persistencemay be provided through persistent coordinate frames (PCFs). A PCF maybe defined based on one or more points, representing features recognizedin the physical world (e.g., corners, edges). The features may beselected such that they are likely to be the same from a user instanceto another user instance of an XR system.

Further, drift during tracking, which causes the computed tracking path(e.g., camera trajectory) to deviate from the actual tracking path, cancause the location of virtual content, when rendered with respect to alocal map that is based solely on a tracking map to appear out of place.A tracking map for the space may be refined to correct the drifts as anXR device collects more information of the scene overtime. However, ifvirtual content is placed on a real object before a map refinement andsaved with respect to the world coordinate frame of the device derivedfrom the tracking map, the virtual content may appear displaced, as ifthe real object has been moved during the map refinement. PCFs may beupdated according to map refinement because the PCFs are defined basedon the features and are updated as the features move during maprefinements.

In some embodiments, persistent spatial information may be representedin a way that may be readily shared among users and among thedistributed components, including applications. Information about thephysical world, for example, may be represented as persistent coordinateframes (PCFs). A PCF may be defined based on one or more points thatrepresent features recognized in the physical world. The features may beselected such that they are likely to be the same from user session touser session of the XR system. PCFs may exist sparsely, providing lessthan all of the available information about the physical world, suchthat they may be efficiently processed and transferred. Techniques forprocessing persistent spatial information may include creating dynamicmaps based on one or more coordinate systems in real space across one ormore sessions, and generating persistent coordinate frames (PCF) overthe sparse maps, which may be exposed to XR applications via, forexample, an application programming interface (API). These capabilitiesmay be supported by techniques for ranking and merging multiple mapscreated by one or more XR devices. Persistent spatial information mayalso enable quickly recovering and resetting head poses on each of oneor more XR devices in a computationally efficient way.

A PCF may comprise six degrees of freedom with translations androtations relative to a map coordinate system. A PCF may be stored in alocal and/or remote storage medium. The translations and rotations of aPCF may be computed relative to a map coordinate system depending on,for example, the storage location. For example, a PCF used locally by adevice may have translations and rotations relative to a worldcoordinate frame of the device. A PCF in the cloud may have translationsand rotations relative to a canonical coordinate frame of a canonicalmap.

PCFs may provide a sparse representation of the physical world,providing less than all of the available information about the physicalworld, such that they may be efficiently processed and transferred.Techniques for processing persistent spatial information may includecreating dynamic maps based on one or more coordinate systems in realspace across one or more sessions, generating persistent coordinateframes (PCF) over the sparse maps, which may be exposed to XRapplications via, for example, an application programming interface(API).

FIG. 14 is a block diagram illustrating the creation of a persistentcoordinate frame (PCF) and the attachment of XR content to the PCF,according to some embodiments. Each block may represent digitalinformation stored in a computer memory. In the case of applications1180, the data may represent computer-executable instructions. In thecase of virtual content 1170, the digital information may define avirtual object, as specified by the application 1180, for example. Inthe case of the other boxes, the digital information may characterizesome aspect of the physical world.

In the illustrated embodiment, one or more PCFs are created from imagescaptured with sensors on a wearable device. In the embodiment of FIG. 14, the sensors are visual image cameras. These cameras may be the samecameras used for forming a tracking map. Accordingly, some of theprocessing suggested by FIG. 14 may be performed as part of updating atracking map. However, FIG. 14 illustrates that information thatprovides persistence is generated in addition to the tracking map.

In order to derive a 3D PCF, two images 1110 from two cameras mounted toa wearable device in a configuration that enables stereoscopic imageanalysis are processed together. FIG. 14 illustrates an Image 1 and anImage 2, each derived from one of the cameras. A single image from eachcamera is illustrated for simplicity. However, each camera may output astream of image frames and the processing illustrated in FIG. 14 may beperformed for multiple image frames in the stream.

Accordingly, Image 1 and Image 2 may each be one frame in a sequence ofimage frames. Processing as depicted in FIG. 14 may be repeated onsuccessive image frames in the sequence until image frames containingfeature points providing a suitable image from which to form persistentspatial information is processed. Alternatively, or additionally, theprocessing of FIG. 14 might be repeated as a user moves such that theuser is no longer close enough to a previously identified PCF toreliably use that PCF for determining positions with respect to thephysical world. For example, an XR system may maintain a current PCF fora user. When that distance exceeds a threshold, the system may switch toa new current PCF, closer to the user, which may be generated accordingto the process of FIG. 14 , using image frames acquired in the user'scurrent location.

Even when generating a single PCF, a stream of image frames may beprocessed to identify image frames depicting content in the physicalworld that is likely stable and can be readily identified by a device inthe vicinity of the region of the physical world depicted in the imageframe. In the embodiment of FIG. 14 , this processing begins with theidentification of features 1120 in the image. Features may beidentified, for example, by finding locations of gradients in the imageabove a threshold or other characteristics, which may correspond to acorner of an object, for example. In the embodiment illustrated, thefeatures are points, but other recognizable features, such as edges, mayalternatively or additionally be used.

In the embodiment illustrated, a fixed number, N, of features 1120 areselected for further processing. Those feature points may be selectedbased on one or more criteria, such as magnitude of the gradient, orproximity to other feature points. Alternatively, or additionally, thefeature points may be selected heuristically, such as based oncharacteristics that suggest the feature points are persistent. Forexample, heuristics may be defined based on the characteristics offeature points that likely correspond to a corner of a window or a dooror a large piece of furniture. Such heuristics may take into account thefeature point itself and what surrounds it. As a specific example, thenumber of feature points per image may be between 100 and 500 or between150 and 250, such as 200.

Regardless of the number of feature points selected, descriptors 1130may be computed for the feature points. In this example, a descriptor iscomputed for each selected feature point, but a descriptor may becomputed for groups of feature points or for a subset of the featurepoints or for all features within an image. The descriptor characterizesa feature point such that feature points representing the same object inthe physical world are assigned similar descriptors. The descriptors mayfacilitate alignment of two frames, such as may occur when one map islocalized with respect to another. Rather than searching for a relativeorientation of the frames that minimizes the distance between featurepoints of the two images, an initial alignment of the two frames may bemade by identifying feature points with similar descriptors. Alignmentof the image frames may be based on aligning points with similardescriptors, which may entail less processing than computing analignment of all the feature points in the images.

The descriptors may be computed as a mapping of the feature points or,in some embodiments a mapping of a patch of an image around a featurepoint, to a descriptor. The descriptor may be a numeric quantity. U.S.patent application Ser. No. 16/190,948 describes computing descriptorsfor feature points and is hereby incorporated herein by reference in itsentirety.

In the example of FIG. 14 , a descriptor 1130 is computed for eachfeature point in each image frame. Based on the descriptors and/or thefeature points and/or the image itself, the image frame may beidentified as a key frame 1140. In the embodiment illustrated, a keyframe is an image frame meeting certain criteria that is then selectedfor further processing. In making a tracking map, for example, imageframes that add meaningful information to the map may be selected as keyframes that are integrated into the map. On the other hand, image framesthat substantially overlap a region for which an image frame has alreadybeen integrated into the map may be discarded such that they do notbecome key frames. Alternatively, or additionally, key frames may beselected based on the number and/or type of feature points in the imageframe. In the embodiment of FIG. 14 , key frames 1150 selected forinclusion in a tracking map may also be treated as key frames fordetermining a PCF, but different or additional criteria for selectingkey frames for generation of a PCF may be used.

Though FIG. 14 shows that a key frame is used for further processing,information acquired from an image may be processed in other forms. Forexample, the feature points, such as in a key rig, may alternatively oradditionally be processed. Moreover, though a key frame is described asbeing derived from a single image frame, it is not necessary that therebe a one-to-one relationship between a key frame and an acquired imageframe. A key frame, for example, may be acquired from multiple imageframes, such as by stitching together or aggregating the image framessuch that only features appearing in multiple images are retained in thekey frame.

A key frame may include image information and/or metadata associatedwith the image information. In some embodiments, images captured by thecameras 44, 46 (FIG. 9 ) may be computed into one or more key frames(e.g., key frames 1, 2). In some embodiments, a key frame may include acamera pose. In some embodiments, a key frame may include one or morecamera images captured at the camera pose. In some embodiments, an XRsystem may determine a portion of the camera images captured at thecamera pose as not useful and thus not include the portion in a keyframe. Therefore, using key frames to align new images with earlierknowledge of a scene reduces the use of computational resource of the XRsystem. In some embodiments, a key frame may include an image, and/orimage data, at a location with a direction/angle. In some embodiments, akey frame may include a location and a direction from which one or moremap points may be observed. In some embodiments, a key frame may includea coordinate frame with an ID. U.S. patent application Ser. No.15/877,359 describes key frames and is hereby incorporated herein byreference in its entirety.

Some or all of the key frames 1140 may be selected for furtherprocessing, such as the generation of a persistent pose 1150 for the keyframe. The selection may be based on the characteristics of all, or asubset of, the feature points in the image frame. Those characteristicsmay be determined from processing the descriptors, features and/or imageframe, itself. As a specific example, the selection may be based on acluster of feature points identified as likely to relate to a persistentobject.

Each key frame is associated with a pose of the camera at which that keyframe was acquired. For key frames selected for processing into apersistent pose, that pose information may be saved along with othermetadata about the key frame, such as a Wi-Fi fingerprint and/or GPScoordinates at the time of acquisition and/or at the location ofacquisition. In some embodiments, the metadata, for example the GPScoordinates, may individually or in combination be used as a part of thelocalization process.

The persistent poses are a source of information that a device may useto orient itself relative to previously acquired information about thephysical world. For example, if the key frame from which a persistentpose was created is incorporated into a map of the physical world, adevice may orient itself relative to that persistent pose using asufficient number of feature points in the key frame that are associatedwith the persistent pose. The device may align a current image that ittakes of its surroundings to the persistent pose. This alignment may bebased on matching the current image to the image 1110, the features1120, and/or the descriptors 1130 that gave rise to the persistent pose,or any subset of that image or those features or descriptors. In someembodiments, the current image frame that is matched to the persistentpose may be another key frame that has been incorporated into thedevice's tracking map.

Information about a persistent pose may be stored in a format thatfacilitates sharing among multiple applications, which may be executingon the same or different devices. In the example of FIG. 14 , some orall of the persistent poses may be reflected as a persistent coordinateframes (PCFs) 1160. Like a persistent pose, a PCF may be associated witha map and may comprise a set of features, or other information, that adevice can use to determine its orientation with respect to that PCF.The PCF may include a transformation that defines its transformationwith respect to the origin of its map, such that, by correlating itsposition to a PCF, the device can determine its position with respect toany objects in the physical world reflected in the map.

As the PCF provides a mechanism for determining locations with respectto the physical objects, an application, such as applications 1180, maydefine positions of virtual objects with respect to one or more PCFs,which serve as anchors for the virtual content 1170. FIG. 14illustrates, for example, that App 1 has associated its virtual content2 with PCF 1.2. Likewise, App 2 has associated its virtual content 3with PCF 1.2. App 1 is also shown associating its virtual content 1 toPCF 4.5, and App 2 is shown associating its virtual content 4 with PCF3. In some embodiments, PCF 3 may be based on Image 3 (not shown), andPCF 4.5 may be based on Image 4 and Image 5 (not shown) analogously tohow PCF 1.2 is based on Image 1 and Image 2. When rendering this virtualcontent, a device may apply one or more transformations to computeinformation, such as the location of the virtual content with respect tothe display of the device and/or the location of physical objects withrespect to the desired location of the virtual content. Using the PCFsas reference may simplify such computations.

In some embodiments, a persistent pose may be a coordinate locationand/or direction that has one or more associated key frames. In someembodiments, a persistent pose may be automatically created after theuser has traveled a certain distance, e.g., three meters. In someembodiments, the persistent poses may act as reference points duringlocalization. In some embodiments, the persistent poses may be stored ina passable world (e.g., the passable world module 538).

In some embodiments, a new PCF may be determined based on a pre-defineddistance allowed between adjacent PCFs. In some embodiments, one or morepersistent poses may be computed into a PCF when a user travels apredetermined distance, e.g., five meters. In some embodiments, PCFs maybe associated with one or more world coordinate frames and/or canonicalcoordinate frames, e.g., in the passable world. In some embodiments,PCFs may be stored in a local and/or remote database depending on, forexample, security settings.

FIG. 15 illustrates a method 4700 of establishing and using apersistence coordinate frame, according to some embodiments. The method4700 may start from capturing (Act 4702) images (e.g., Image 1 and Image2 in FIG. 14 ) about a scene using one or more sensors of an XR device.Multiple cameras may be used and one camera may generate multipleimages, for example, in a stream.

The method 4700 may include extracting (4704) interest points (e.g., mappoints 702 in FIG. 7 , features 1120 in FIG. 14 ) from the capturedimages, generating (Act 4706) descriptors (e.g., descriptors 1130 inFIG. 14 ) for the extracted interest points, and generating (Act 4708)key frames (e.g., key frames 1140) based on the descriptors. In someembodiments, the method may compare interest points in the key frames,and form pairs of key frames that share a predetermined amount ofinterest points. The method may reconstruct parts of the physical worldusing individual pairs of key frames. Mapped parts of the physical worldmay be saved as 3D features (e.g., keyrig 704 in FIG. 7 ). In someembodiments, a selected portion of the pairs of key frames may be usedto build 3D features. In some embodiments, results of the mapping may beselectively saved. Key frames not used for building 3D features may beassociated with the 3D features through poses, for example, representingdistances between key frames with a covariance matrix between poses ofkeyframes. In some embodiments, pairs of key frames may be selected tobuild the 3D features such that distances between each two of the build3D features are within a predetermined distance, which may be determinedto balance the amount of computation needed and the level of accuracy ofa resulting model. Such approaches enable providing a model of thephysical world with the amount of data that is suitable for efficientand accurate computation with an XR system. In some embodiments, acovariance matrix of two images may include covariances between poses ofthe two images (e.g., six degree of freedom).

The method 4700 may include generating (Act 4710) persistent poses basedon the key frames. In some embodiments, the method may includegenerating the persistent poses based on the 3D features reconstructedfrom pairs of key frames. In some embodiments, a persistent pose may beattached to a 3D feature. In some embodiments, the persistent pose mayinclude a pose of a key frame used to construct the 3D feature. In someembodiments, the persistent pose may include an average pose of keyframes used to construct the 3D feature. In some embodiments, persistentposes may be generated such that distances between neighboringpersistent poses are within a predetermined value, for example, in therange of one meter to five meters, any value in between, or any othersuitable value. In some embodiments, the distances between neighboringpersistent poses may be represented by a covariance matrix of theneighboring persistent poses.

The method 4700 may include generating (Act 4712) PCFs based on thepersistent poses. In some embodiments, a PCF may be attached to a 3Dfeature. In some embodiments, a PCF may be associated with one or morepersistent poses. In some embodiments, a PCF may include a pose of oneof the associated persistent poses. In some embodiments, a PCF mayinclude an average pose of the poses of the associated persistent poses.In some embodiments, PCFs may be generated such that distances betweenneighboring PCFs are within a predetermined value, for example, in therange of three meters to ten meters, any value in between, or any othersuitable value. In some embodiments, the distances between neighboringPCFs may be represented by a covariance matrix of the neighboring PCFs.In some embodiments, PCFs may be exposed to XR applications via, forexample, an application programming interface (API) such that the XRapplications can access a model of the physical world through the PCFswithout accessing the model itself.

The method 4700 may include associating (Act 4714) image data of avirtual object to be displayed by the XR device to at least one of thePCFs. In some embodiments, the method may include computing translationsand orientations of the virtual object with respect to the associatedPCF. It should be appreciated that it is not necessary to associate avirtual object to a PCF generated by the device placing the virtualobject. For example, a device may retrieve saved PCFs in a canonical mapin a cloud and associate a virtual object to a retrieved PCF. It shouldbe appreciated that the virtual object may move with the associated PCFas the PCF is adjusted overtime.

FIG. 16 illustrates the first XR device 12.1 and vision data andalgorithms of a second XR device 12.2 and the server 20, according tosome embodiments. The components illustrated in FIG. 16 may operate toperform some or all of the operations associated with generating,updating, and/or using spatial information, such as persistent poses,persistent coordinate frames, tracking maps, or canonical maps, asdescribed herein. Although not illustrated, the first XR device 12.1 maybe configured the same as the second XR device 12.2. The server 20 mayhave a map storing routine 118, a canonical map 120, a map transmitter122, and a map merge algorithm 124.

The second XR device 12.2, which may be in the same scene as the firstXR device 12.1, may include a persistent coordinate frame (PCF)integration unit 1300, an application 1302 that generates the image data68 that may be used to render a virtual object, and a frame embeddinggenerator 308 (See FIG. 21 ). In some embodiments, a map download system126, PCF identification system 128, Map 2, localization module 130,canonical map incorporator 132, canonical map 133, and map publisher 136may be grouped into a passable world unit 1304. The PCF integration unit1300 may be connected to the passable world unit 1304 and othercomponents of the second XR device 12.2 to allow for the retrieval,generation, use, upload, and download of PCFs.

A map, comprising PCFs, may enable more persistence in a changing world.In some embodiments, localizing a tracking map including, for example,matching features for images, may include selecting features thatrepresent persistent content from the map constituted by PCFs, whichenables fast matching and/or localizing. For example, a world wherepeople move into and out of the scene and objects such as doors moverelative to the scene, requires less storage space and transmissionrates, and enables the use of individual PCFs and their relationshipsrelative to one another (e.g., integrated constellation of PCFs) to mapa scene.

In some embodiments, the PCF integration unit 1300 may include PCFs 1306that were previously stored in a data store on a storage unit of thesecond XR device 12.2, a PCF tracker 1308, a persistent pose acquirer1310, a PCF checker 1312, a PCF generation system 1314, a coordinateframe calculator 1316, a persistent pose calculator 1318, and threetransformers, including a tracking map and persistent pose transformer1320, a persistent pose and PCF transformer 1322, and a PCF and imagedata transformer 1324.

In some embodiments, the PCF tracker 1308 may have an on-prompt and anoff-prompt that are selectable by the application 1302. The application1302 may be executable by a processor of the second XR device 12.2 to,for example, display a virtual content. The application 1302 may have acall that switches the PCF tracker 1308 on via the on-prompt. The PCFtracker 1308 may generate PCFs when the PCF tracker 1308 is switched on.The application 1302 may have a subsequent call that can switch the PCFtracker 1308 off via the off-prompt. The PCF tracker 1308 terminates PCFgeneration when the PCF tracker 1308 is switched off.

In some embodiments, the server 20 may include a plurality of persistentposes 1332 and a plurality of PCFs 1330 that have previously been savedin association with a canonical map 120. The map transmitter 122 maytransmit the canonical map 120 together with the persistent poses 1332and/or the PCFs 1330 to the second XR device 12.2. The persistent poses1332 and PCFs 1330 may be stored in association with the canonical map133 on the second XR device 12.2. When Map 2 localizes to the canonicalmap 133, the persistent poses 1332 and the PCFs 1330 may be stored inassociation with Map 2.

In some embodiments, the persistent pose acquirer 1310 may acquire thepersistent poses for Map 2. The PCF checker 1312 may be connected to thepersistent pose acquirer 1310. The PCF checker 1312 may retrieve PCFsfrom the PCFs 1306 based on the persistent poses retrieved by thepersistent pose acquirer 1310. The PCFs retrieved by the PCF checker1312 may form an initial group of PCFs that are used for image displaybased on PCFs.

In some embodiments, the application 1302 may require additional PCFs tobe generated. For example, if a user moves to an area that has notpreviously been mapped, the application 1302 may switch the PCF tracker1308 on. The PCF generation system 1314 may be connected to the PCFtracker 1308 and begin to generate PCFs based on Map 2 as Map 2 beginsto expand. The PCFs generated by the PCF generation system 1314 may forma second group of PCFs that may be used for PCF-based image display.

The coordinate frame calculator 1316 may be connected to the PCF checker1312. After the PCF checker 1312 retrieved PCFs, the coordinate framecalculator 1316 may invoke the head coordinate frame 96 to determine ahead pose of the second XR device 12.2. The coordinate frame calculator1316 may also invoke the persistent pose calculator 1318. The persistentpose calculator 1318 may be directly or indirectly connected to theframe embedding generator 308. In some embodiments, an image/frame maybe designated a key frame after a threshold distance from the previouskey frame, e.g., 3 meters, is traveled. The persistent pose calculator1318 may generate a persistent pose based on a plurality, for examplethree, key frames. In some embodiments, the persistent pose may beessentially an average of the coordinate frames of the plurality of keyframes.

The tracking map and persistent pose transformer 1320 may be connectedto Map 2 and the persistent pose calculator 1318. The tracking map andpersistent pose transformer 1320 may transform Map 2 to the persistentpose to determine the persistent pose at an origin relative to Map 2.

The persistent pose and PCF transformer 1322 may be connected to thetracking map and persistent pose transformer 1320 and further to the PCFchecker 1312 and the PCF generation system 1314. The persistent pose andPCF transformer 1322 may transform the persistent pose (to which thetracking map has been transformed) to the PCFs from the PCF checker 1312and the PCF generation system 1314 to determine the PCFs relative to thepersistent pose.

The PCF and image data transformer 1324 may be connected to thepersistent pose and PCF transformer 1322 and to the data channel 62. ThePCF and image data transformer 1324 transforms the PCFs to the imagedata 68. The rendering engine 30 may be connected to the PCF and imagedata transformer 1324 to display the image data 68 to the user relativeto the PCFs.

The PCF integration unit 1300 may store the additional PCFs that aregenerated with the PCF generation system 1314 within the PCFs 1306. ThePCFs 1306 may be stored relative to persistent poses. The map publisher136 may retrieve the PCFs 1306 and the persistent poses associated withthe PCFs 1306 when the map publisher 136 transmits Map 2 to the server20, the map publisher 136 also transmits the PCFs and persistent posesassociated with Map 2 to the server 20. When the map storing routine 118of the server 20 stores Map 2, the map storing routine 118 may alsostore the persistent poses and PCFs generated by the second viewingdevice 12.2. The map merge algorithm 124 may create the canonical map120 with the persistent poses and PCFs of Map 2 associated with thecanonical map 120 and stored within the persistent poses 1332 and PCFs1330, respectively.

The first XR device 12.1 may include a PCF integration unit similar tothe PCF integration unit 1300 of the second XR device 12.2. When the maptransmitter 122 transmits the canonical map 120 to the first XR device12.1, the map transmitter 122 may transmit the persistent poses 1332 andPCFs 1330 associated with the canonical map 120 and originating from thesecond XR device 12.2. The first XR device 12.1 may store the PCFs andthe persistent poses within a data store on a storage device of thefirst XR device 12.1. The first XR device 12.1 may then make use of thepersistent poses and the PCFs originating from the second XR device 12.2for image display relative to the PCFs. Additionally or alternatively,the first XR device 12.1 may retrieve, generate, make use, upload, anddownload PCFs and persistent poses in a manner similar to the second XRdevice 12.2 as described above.

In the illustrated example, the first XR device 12.1 generates a localtracking map (referred to hereinafter as “Map 1”) and the map storingroutine 118 receives Map 1 from the first XR device 12.1. The mapstoring routine 118 then stores Map 1 on a storage device of the server20 as the canonical map 120.

The second XR device 12.2 includes a map download system 126, an anchoridentification system 128, a localization module 130, a canonical mapincorporator 132, a local content position system 134, and a mappublisher 136.

In use, the map transmitter 122 sends the canonical map 120 to thesecond XR device 12.2 and the map download system 126 downloads andstores the canonical map 120 as a canonical map 133 from the server 20.

The anchor identification system 128 is connected to the world surfacedetermining routine 78. The anchor identification system 128 identifiesanchors based on objects detected by the world surface determiningroutine 78. The anchor identification system 128 generates a second map(Map 2) using the anchors. As indicated by the cycle 138, the anchoridentification system 128 continues to identify anchors and continues toupdate Map 2. The locations of the anchors are recorded asthree-dimensional data based on data provided by the world surfacedetermining routing 78. The world surface determining routine 78receives images from the real object detection camera 44 and depth datafrom depth sensors 135 to determine the locations of surfaces and theirrelative distance from the depth sensors 135

The localization module 130 is connected to the canonical map 133 andMap 2. The localization module 130 repeatedly attempts to localize Map 2to the canonical map 133. The canonical map incorporator 132 isconnected to the canonical map 133 and Map 2. When the localizationmodule 130 localizes Map 2 to the canonical map 133, the canonical mapincorporator 132 incorporates the canonical map 133 into anchors of Map2. Map 2 is then updated with missing data that is included in thecanonical map.

The local content position system 134 is connected to Map 2. The localcontent position system 134 may, for example, be a system wherein a usercan locate local content in a particular location within a worldcoordinate frame. The local content then attaches itself to one anchorof Map 2. The local-to-world coordinate transformer 104 transforms thelocal coordinate frame to the world coordinate frame based on thesettings of the local content position system 134. The functioning ofthe rendering engine 30, display system 42, and data channel 62 havebeen described with reference to FIG. 2 .

The map publisher 136 uploads Map 2 to the server 20. The map storingroutine 118 of the server 20 then stores Map 2 within a storage mediumof the server 20.

The map merge algorithm 124 merges Map 2 with the canonical map 120.When more than two maps, for example, three or four maps relating to thesame or adjacent regions of the physical world, have been stored, themap merge algorithm 124 merges all the maps into the canonical map 120to render a new canonical map 120. The map transmitter 122 thentransmits the new canonical map 120 to any and all devices 12.1 and 12.2that are in an area represented by the new canonical map 120. When thedevices 12.1 and 12.2 localize their respective maps to the canonicalmap 120, the canonical map 120 becomes the promoted map.

FIG. 17 illustrates an example of generating key frames for a map of ascene, according to some embodiments. In the illustrated example, afirst key frame, KF1, is generated for a door on a left wall of theroom. A second key frame, KF2, is generated for an area in a cornerwhere a floor, the left wall, and a right wall of the room meet. A thirdkey frame, KF3, is generated for an area of a window on the right wallof the room. A fourth key frame, KF4, is generated for an area at a farend of a rug on a floor of the wall. A fifth key frame, KF5, isgenerated for an area of the rug closest to the user.

FIG. 18 illustrates an example of generating persistent poses for themap of FIG. 17 , according to some embodiments. In some embodiments, anew persistent pose is created when the device measures a thresholddistance traveled, and/or when an application requests a new persistentpose (PP). In some embodiments, the threshold distance may be 3 meters,5 meters, 20 meters, or any other suitable distance. Selecting a smallerthreshold distance (e.g., 1 m) may result in an increase in compute loadsince a larger number of PPs may be created and managed compared tolarger threshold distances. Selecting a larger threshold distance (e.g.,40 m) may result in increased virtual content placement error since asmaller number of PPs would be created, which would result in fewer PCFsbeing created, which means the virtual content attached to the PCF couldbe a relatively large distance (e.g., 30 m) away from the PCF, and errorincreases with increasing distance from a PCF to the virtual content.

In some embodiments, a PP may be created at the start of a new session.This initial PP may be thought of as zero, and can be visualized as thecenter of a circle that has a radius equal to the threshold distance.When the device reaches the perimeter of the circle, and, in someembodiments, an application requests a new PP, a new PP may be placed atthe current location of the device (at the threshold distance). In someembodiments, a new PP will not be created at the threshold distance ifthe device is able to find an existing PP within the threshold distancefrom the device's new position. In some embodiments, when a new PP(e.g., PP1150 in FIG. 14 ) is created, the device attaches one or moreof the closest key frames to the PP. In some embodiments, the locationof the PP relative to the key frames may be based on the location of thedevice at the time a PP is created. In some embodiments, a PP will notbe created when the device travels a threshold distance unless anapplication requests a PP.

In some embodiments, an application may request a PCF from the devicewhen the application has virtual content to display to the user. The PCFrequest from the application may trigger a PP request, and a new PPwould be created after the device travels the threshold distance. FIG.18 illustrates a first persistent pose PP1 which may have the closestkey frames, (e.g., KF1, KF2, and KF3) attached by, for example,computing relative poses between the key frames to the persistent pose.FIG. 18 also illustrates a second persistent pose PP2 which may have theclosest key frames (e.g., KF4 and KF5) attached.

FIG. 19 illustrates an example of generating a PCF for the map of FIG.17 , according to some embodiments. In the illustrated example, a PCF 1may include PP1 and PP2. As described above, the PCF may be used fordisplaying image data relative to the PCF. In some embodiments, each PCFmay have coordinates in another coordinate frame (e.g., a worldcoordinate frame) and a PCF descriptor, for example, uniquelyidentifying the PCF. In some embodiments, the PCF descriptor may becomputed based on feature descriptors of features in frames associatedwith the PCF. In some embodiments, various constellations of PCFs may becombined to represent the real world in a persistent manner and thatrequires less data and less transmission of data.

FIGS. 20A to 20C are schematic diagrams illustrating an example ofestablishing and using a persistent coordinate frame. FIG. 20A shows twousers 4802A, 4802B with respective local tracking maps 4804A, 4804B thathave not localized to a canonical map. The origins 4806A, 4806B forindividual users are depicted by the coordinate system (e.g., a worldcoordinate system) in their respective areas. These origins of eachtracking map may be local to each user, as the origins are dependent onthe orientation of their respective devices when tracking was initiated.

As the sensors of the user device scan the environment, the device maycapture images that, as described above in connection with FIG. 14 , maycontain features representing persistent objects such that those imagesmay be classified as key frames, from which a persistent pose may becreated. In this example, the tracking map 4802A includes a persistentpose (PP) 4808A; the tracking 4802B includes a PP 4808B.

Also as described above in connection with FIG. 14 , some of the PPs maybe classified as PCFs which are used to determine the orientation ofvirtual content for rendering it to the user. FIG. 20B shows that XRdevices worn by respective users 4802A, 4802B may create local PCFs4810A, 4810B based on the PP 4808A, 4808B. FIG. 20C shows thatpersistent content 4812A, 4812B (e.g., a virtual content) may beattached to the PCFs 4810A, 4810B by respective XR devices.

In this example, virtual content may have a virtual content coordinateframe, that may be used by an application generating virtual content,regardless of how the virtual content should be displayed. The virtualcontent, for example, may be specified as surfaces, such as triangles ofa mesh, at particular locations and angles with respect to the virtualcontent coordinate frame. To render that virtual content to a user, thelocations of those surfaces may be determined with respect to the userthat is to perceive the virtual content.

Attaching virtual content to the PCFs may simplify the computationinvolved in determining locations of the virtual content with respect tothe user. The location of the virtual content with respect to a user maybe determined by applying a series of transformations. Some of thosetransformations may change, and may be updated frequently. Others ofthose transformations may be stable and may be updated in frequently ornot at all. Regardless, the transformations may be applied withrelatively low computational burden such that the location of thevirtual content can be updated with respect to the user frequently,providing a realistic appearance to the rendered virtual content.

In the example of FIGS. 20A-20C, user 1's device has a coordinate systemthat can be related to the coordinate system that defines the origin ofthe map by the transformation rig1_T_w1. User 2's device has a similartransformation rig2_T_w2. These transformations may be expressed as 6degree of transformation, specifying translation and rotation to alignthe device coordinate systems with the map coordinate systems. In someembodiments, the transformation may be expressed as two separatetransformations, one specifying translation and the other specifyingrotation. Accordingly, it should be appreciated that the transformationsmay be expressed in a form that simplifies computation or otherwiseprovides an advantage.

Transformations between the origins of the tracking maps and the PCFsidentified by the respective user devices are expressed as pcf1_T_w1 andpcf2_T_w2. In this example the PCF and the PP are identical, such thatthe same transformation also characterizes the PPs.

The location of the user device with respect to the PCF can therefore becomputed by the serial application of these transformations, such asrig1_T_pcf1=(rig1_T_w1)*(pcf1_T_w1).

As shown in FIG. 20C, the virtual content is located with respect to thePCFs, with a transformation of obj1_T_pcf1. This transformation may beset by an application generating the virtual content that may receiveinformation from a world reconstruction system describing physicalobjects with respect to the PCF. To render the virtual content to theuser, a transformation to the coordinate system of the user's device iscomputed, which may be computed by relating the virtual contentcoordinate frame to the origin of the tracking map through thetransformation obj1_t_w1=(obj1_T_pcf1)*(pcf1_T_w1). That transformationmay then be related to the user's device through further transformationrig1_T_w1.

The location of the virtual content may change, based on output from anapplication generating the virtual content. When that changes, theend-to-end transformation, from a source coordinate system to adestination coordinate system, may be recomputed. Additionally, thelocation and/or head pose of the user may change as the user moves. As aresult, the transformation rig1_T_w1 may change, as would any end-to-endtransformation that depends on the location or head pose of the user.

The transformation rig1_T_w1 may be updated with motion of the userbased on tracking the position of the user with respect to stationaryobjects in the physical world. Such tracking may be performed by aheadpose tracking component processing a sequence of images, asdescribed above, or other component of the system. Such updates may bemade by determining pose of the user with respect to a stationary frameof reference, such as a PP.

In some embodiments, the location and orientation of a user device maybe determined relative to the nearest persistent pose, or, in thisexample, a PCF, as the PP is used as a PCF. Such a determination may bemade by identifying in current images captured with sensors on thedevice feature points that characterize the PP. Using image processingtechniques, such as stereoscopic image analysis, the location of thedevice with respect to those feature points may be determined. From thisdata, the system could calculate the change in transformation associatedwith the user's motions based on the relationshiprig1_T_pcf1=(rig1_T_w1)*(pcf1_T_w1).

A system may determine and apply transformations in an order that iscomputationally efficient. For example, the need to compute rig1_T_w1from a measurement yielding rig1_T_pcf1 might be avoided by trackinguser pose and defining the location of virtual content relative to thePP or a PCF built on a persistent pose. In this way the transformationfrom a source coordinate system of the virtual content to thedestination coordinate system of the user's device may be based on themeasured transformation according to the expression(rig1_T_pcf1)*(obj1_t_pcf1), with the first transformation beingmeasured by the system and the latter transformation being supplied byan application specifying virtual content for rendering. In embodimentsin which the virtual content is positioned with respect to the origin ofthe map, the end-to-end transformation may relate the virtual objectcoordinate system to the PCF coordinate system based on a furthertransformation between the map coordinates and the PCF coordinates. Inembodiments in which the virtual content is positioned with respect to adifferent PP or PCF than the one against which user position is beingtracked, a transformation between the two may be applied. Such atransformation may be fixed and may be determined, for example, from amap in which both appear.

A transform-based approach may be implemented, for example, in a devicewith components that process sensor data to build a tracking map. Aspart of that process, those components may identify feature points thatmay be used as persistent poses, which in turn may be turned into PCFs.Those components may limit the number of persistent poses generated forthe map, to provide a suitable spacing between persistent poses, whileallowing the user, regardless of location in the physical environment,to be close enough to a persistent pose location to accurately computethe user's pose, as described above in connection with FIGS. 17-19 . Asthe closest persistent pose to a user is updated, as a result of usermovement, refinements to the tracking map or other causes, any of thetransformations that are used to compute the location of virtual contentrelative to the user that depend on the location of the PP (or PCF ifbeing used) may be updated and stored for use, at least until the usermoves away from that persistent pose. Nonetheless, by computing andstoring transformations, the computational burden each time the locationof virtual content is update may be relatively low, such that it may beperformed with relatively low latency.

FIGS. 20A-20C illustrate positioning with respect to a tracking map, andeach device had its own tracking map. However, transformations may begenerated with respect to any map coordinate system. Persistence ofcontent across user sessions of an XR system may be achieved by using apersistent map. Shared experiences of users may also be facilitated byusing a map to which multiple user devices may be oriented.

In some embodiments, described in greater detail below, the location ofvirtual content may be specified in relation to coordinates in acanonical map, formatted such that any of multiple devices may use themap. Each device might maintain a tracking map and may determine thechange of pose of the user with respect to the tracking map. In thisexample, a transformation between the tracking map and the canonical mapmay be determined through a process of “localization”—which may beperformed by matching structures in the tracking map (such as one ormore persistent poses) to one or more structures of the canonical map(such as one or more PCFs).

Described in greater below are techniques for creating and usingcanonical maps in this way.

Deep Key Frame

Techniques as described herein rely on comparison of image frames. Forexample, to establish the position of a device with respect to atracking map, a new image may be captured with sensors worn by the userand an XR system may search, in a set of images that were used to createthe tracking map, images that share at least a predetermined amount ofinterest points with the new image. As an example of another scenarioinvolving comparisons of image frames, a tracking map might be localizedto a canonical map by first finding image frames associated with apersistent pose in the tracking map that is similar to an image frameassociated with a PCF in the canonical map. Alternatively, atransformation between two canonical maps may be computed by firstfinding similar image frames in the two maps.

Techniques as described herein may enable efficient comparison ofspatial information. In some embodiments, an image frame may berepresented by a numeric descriptor. That descriptor may be computed viaa transformation that maps a set of features identified in the image tothe descriptor. That transformation may be performed in a trained neuralnetwork. In some embodiments, the set of features that is supplied as aninput to the neural network may be a filtered set of features, extractedfrom the image using techniques, for example, that preferentially selectfeatures that are likely to be persistent.

The representation of image frames as a descriptor enables, for example,efficient matching of new image information to stored image information.An XR system may store in conjunction with persistent maps descriptorsof one or more frames underlying the persistent map. A local image frameacquired by a user device may similarly be converted to such adescriptor. By selecting stored maps with descriptors similar to that ofthe local image frame, one or more persistent maps likely representingthe same physical space as the user device may be selected with arelatively small amount of processing. In some embodiments, thedescriptor may be computed for key frames in the local map and thepersistent map, further reducing processing when comparing maps. Such anefficient comparison may be used, for example, to simplify finding apersistent map to load in a local device or to find a persistent map toupdate based on image information acquired with a local device.

Deep key frames provide a way to reduce the amount of processingrequired to identify similar image frames. For example, in someembodiments, the comparison may be between image features in a new 2Dimage (e.g., “2D features”) and 3D features in the map. Such acomparison may be made in any suitable way, such as by projecting the 3Dimages into a 2D plane. A conventional method such as Bag of Words (BoW)searches the 2D features of a new image in a database including all 2Dfeatures in a map, which may require significant computing resourcesespecially when a map represents a large area. The conventional methodthen locates the images that share at least one of the 2D features withthe new image, which may include images that are not useful for locatingmeaningful 3D features in the map. The conventional method then locates3D features that are not meaningful with respect to the 2D features inthe new image.

The inventors have recognized and appreciated techniques to retrieveimages in the map using less memory resource (e.g., a quarter of thememory resource used by BoW), higher efficiency (e.g., 2.5 ms processingtime for each key frame, 100 μs for comparing against 500 key frames),and higher accuracy (e.g., 20% better retrieval recall than BoW for1024-dimensional model, 5% better retrieval recall than BoW for256-dimensional model).

To reduce computation, a descriptor may be computed for an image framethat may be used to compare an image frame to other image frames. Thedescriptors may be stored instead of or in addition to the image framesand feature points. In a map in which persistent poses and/or PCFs maybe generated from image frames, the descriptor of the image frame orframes from which each persistent pose or PCF was generated may bestored as part of the persistent pose and/or PCF.

In some embodiments, the descriptor may be computed as a function offeature points in the image frame. In some embodiments, a neural networkis configured to compute a unique frame descriptor to represent animage. The image may have a resolution higher than 1 Megabyte such thatenough details of a 3D environment within a field-of-view of a deviceworn by a user is captured in the image. The frame descriptor may bemuch shorter, such as a string of numbers, for example, in the range of128 Bytes to 512 Bytes or any number in between.

In some embodiments, the neural network is trained such that thecomputed frame descriptors indicate similarity between images. Images ina map may be located by identifying, in a database comprising imagesused to generate the map, the nearest images that may have framedescriptors within a predetermined distance to a frame descriptor for anew image. In some embodiments, the distances between images may berepresented by a difference between the frame descriptors of the twoimages.

FIG. 21 is a block diagram illustrating a system for generating adescriptor for an individual image, according to some embodiments. Inthe illustrated example, a frame embedding generator 308 is shown. Theframe embedding generator 308, in some embodiments, may be used withinthe server 20, but may alternatively or additionally execute in whole orin part within one of the XR devices 12.1 and 12.2, or any other deviceprocessing images for comparison to other images.

In some embodiments, the frame embedding generator may be configured togenerate a reduced data representation of an image from an initial size(e.g., 76,800 bytes) to a final size (e.g., 256 bytes) that isnonetheless indicative of the content in the image despite a reducedsize. In some embodiments, the frame embedding generator may be used togenerate a data representation for an image which may be a key frame ora frame used in other ways. In some embodiments, the frame embeddinggenerator 308 may be configured to convert an image at a particularlocation and orientation into a unique string of numbers (e.g., 256bytes). In the illustrated example, an image 320 taken by an XR devicemay be processed by feature extractor 324 to detect interest points 322in the image 320. Interest points may be or may not be derived fromfeature points identified as described above for features 1120 (FIG. 14) or as otherwise described herein. In some embodiments, interest pointsmay be represented by descriptors as described above for descriptors1130 (FIG. 14 ), which may be generated using a deep sparse featuremethod. In some embodiments, each interest point 322 may be representedby a string of numbers (e.g., 32 bytes). There may, for example, be nfeatures (e.g., 100) and each feature is represented by a string of 32bytes.

In some embodiments, the frame embedding generator 308 may include aneural network 326. The neural network 326 may include a multi-layerperceptron unit 312 and a maximum (max) pool unit 314. In someembodiments, the multi-layer perceptron (MLP) unit 312 may comprise amulti-layer perceptron, which may be trained. In some embodiments, theinterest points 322 (e.g., descriptors for the interest points) may bereduced by the multi-layer perceptron 312, and may output as weightedcombinations 310 of the descriptors. For example, the MLP may reduce nfeatures to m feature that is less than n features.

In some embodiments, the MLP unit 312 may be configured to performmatrix multiplication. The multi-layer perceptron unit 312 receives theplurality of interest points 322 of an image 320 and converts eachinterest point to a respective string of numbers (e.g., 256). Forexample, there may be 100 features and each feature may be representedby a string of 256 numbers. A matrix, in this example, may be createdhaving 100 horizontal rows and 256 vertical columns. Each row may have aseries of 256 numbers that vary in magnitude with some being smaller andothers being larger. In some embodiments, the output of the MLP may bean n×256 matrix, where n represents the number of interest pointsextracted from the image. In some embodiments, the output of the MLP maybe an m×256 matrix, where m is the number of interest points reducedfrom n.

In some embodiments, the MLP 312 may have a training phase, during whichmodel parameters for the MLP are determined, and a use phase. In someembodiments, the MLP may be trained as illustrated in FIG. 25 . Theinput training data may comprise data in sets of three, the set of threecomprising 1) a query image, 2) a positive sample, and 3) a negativesample. The query image may be considered the reference image.

In some embodiments, the positive sample may comprise an image that issimilar to the query image. For example, in some embodiments, similarmay be having the same object in both the query and positive sampleimage but viewed from a different angle. In some embodiments, similarmay be having the same object in both the query and positive sampleimages but having the object shifted (e.g., left, right, up, down)relative to the other image.

In some embodiments, the negative sample may comprise an image that isdissimilar to the query image. For example, in some embodiments, adissimilar image may not contain any objects that are prominent in thequery image or may contain only a small portion of a prominent object inthe query image (e.g., <10%, 1%). A similar image, in contrast, may havemost of an object (e.g., >50%, or >75%) in the query image, for example.

In some embodiments, interest points may be extracted from the images inthe input training data and may be converted to feature descriptors.These descriptors may be computed both for the training images as shownin FIG. 25 and for extracted features in operation of frame embeddinggenerator 308 of FIG. 21 . In some embodiments, a deep sparse feature(DSF) process may be used to generate the descriptors (e.g., DSFdescriptors) as described in U.S. patent application Ser. No.16/190,948. In some embodiments, DSF descriptors are n×32 dimension. Thedescriptors may then be passed through the model/MLP to create a256-byte output. In some embodiments, the model/MLP may have the samestructure as MLP 312 such that once the model parameters are set throughtraining, the resulting trained MLP may be used as MLP 312.

In some embodiments, the feature descriptors (e.g., the 256-byte outputfrom the MLP model) may then be sent to a triplet margin loss module(which may only be used during the training phase, not during use phaseof the MLP neural network). In some embodiments, the triplet margin lossmodule may be configured to select parameters for the model so as toreduce the difference between the 256-byte output from the query imageand the 256-byte output from the positive sample, and to increase thedifference between the 256-byte output from the query image and the256-byte output from the negative sample. In some embodiments, thetraining phase may comprise feeding a plurality of triplet input imagesinto the learning process to determine model parameters. This trainingprocess may continue, for example, until the differences for positiveimages is minimized and the difference for negative images is maximizedor until other suitable exit criteria are reached.

Referring back to FIG. 21 , the frame embedding generator 308 mayinclude a pooling layer, here illustrated as maximum (max) pool unit314. The max pool unit 314 may analyze each column to determine amaximum number in the respective column. The max pool unit 314 maycombine the maximum value of each column of numbers of the output matrixof the MLP 312 into a global feature string 316 of, for example, 256numbers. It should be appreciated that images processed in XR systemsmight, desirably, have high-resolution frames, with potentially millionsof pixels. The global feature string 316 is a relatively small numberthat takes up relatively little memory and is easily searchable comparedto an image (e.g., with a resolution higher than 1 Megabyte). It is thuspossible to search for images without analyzing each original frame fromthe camera and it is also cheaper to store 256 bytes instead of completeframes.

FIG. 22 is a flow chart illustrating a method 2200 of computing an imagedescriptor, according to some embodiments. The method 2200 may startfrom receiving (Act 2202) a plurality of images captured by an XR deviceworn by a user. In some embodiments, the method 2200 may includedetermining (Act 2204) one or more key frames from the plurality ofimages. In some embodiments, Act 2204 may be skipped and/or may occurafter step 2210 instead.

The method 2200 may include identifying (Act 2206) one or more interestpoints in the plurality of images with an artificial neural network, andcomputing (Act 2208) feature descriptors for individual interest pointswith the artificial neural network. The method may include computing(Act 2210), for each image, a frame descriptor to represent the imagebased, at least in part, on the computed feature descriptors for theidentified interest points in the image with the artificial neuralnetwork.

FIG. 23 is a flow chart illustrating a method 2300 of localization usingimage descriptors, according to some embodiments. In this example, a newimage frame, depicting the current location of the XR device may becompared to image frames stored in connection with points in a map (suchas a persistent pose or a PCF as described above). The method 2300 maystart from receiving (Act 2302) a new image captured by an XR deviceworn by a user. The method 2300 may include identifying (Act 2304) oneor more nearest key frames in a database comprising key frames used togenerate one or more maps. In some embodiments, a nearest key frame maybe identified based on coarse spatial information and/or previouslydetermined spatial information. For example, coarse spatial informationmay indicate that the XR device is in a geographic region represented bya 50 m×50 m area of a map. Image matching may be performed only forpoints within that area. As another example, based on tracking, the XRsystem may know that an XR device was previously proximate a firstpersistent pose in the map and was moving in a direction of a secondpersistent pose in the map. That second persistent pose may beconsidered the nearest persistent pose and the key frame stored with itmay be regarded as the nearest key frame. Alternatively, oradditionally, other metadata, such as GPS data or Wi-Fi fingerprints,may be used to select a nearest key frame or set of nearest key frames.

Regardless of how the nearest key frames are selected, frame descriptorsmay be used to determine whether the new image matches any of the framesselected as being associated with a nearby persistent pose. Thedetermination may be made by comparing a frame descriptor of the newimage with frame descriptors of the closest key frames, or a subset ofkey frames in the database selected in any other suitable way, andselecting key frames with frame descriptors that are within apredetermined distance of the frame descriptor of the new image. In someembodiments, a distance between two frame descriptors may be computed byobtaining the difference between two strings of numbers that mayrepresent the two frame descriptors. In embodiments in which the stringsare processed as strings of multiple quantities, the difference may becomputed as a vector difference.

Once a matching image frame is identified, the orientation of the XRdevice relative to that image frame may be determined. The method 2300may include performing (Act 2306) feature matching against 3D featuresin the maps that correspond to the identified nearest key frames, andcomputing (Act 2308) pose of the device worn by the user based on thefeature matching results. In this way, the computationally intensivematching of features points in two images may be performed for as few asone image that has already been determined to be a likely match for thenew image.

FIG. 24 is a flow chart illustrating a method 2400 of training a neuralnetwork, according to some embodiments. The method 2400 may start fromgenerating (Act 2402) a dataset comprising a plurality of image sets.Each of the plurality of image sets may include a query image, apositive sample image, and a negative sample image. In some embodiments,the plurality of image sets may include synthetic recording pairsconfigured to, for example, teach the neural network basic informationsuch as shapes. In some embodiments, the plurality of image sets mayinclude real recording pairs, which may be recorded from a physicalworld.

In some embodiments, inliers may be computed by fitting a fundamentalmatrix between two images. In some embodiments, sparse overlap may becomputed as the intersection over union (IoU) of interest points seen inboth images. In some embodiments, a positive sample may include at leasttwenty interest points, serving as inliers, that are the same as in thequery image. A negative sample may include less than ten inlier points.A negative sample may have less than half of the sparse pointsoverlapping with the sparse points of the query image.

The method 2400 may include computing (Act 2404), for each image set, aloss by comparing the query image with the positive sample image and thenegative sample image. The method 2400 may include modifying (Act 2406)the artificial neural network based on the computed loss such that adistance between a frame descriptor generated by the artificial neuralnetwork for the query image and a frame descriptor for the positivesample image is less than a distance between the frame descriptor forthe query image and a frame descriptor for the negative sample image.

It should be appreciated that although methods and apparatus configuredto generate global descriptors for individual images are describedabove, methods and apparatus may be configured to generate descriptorsfor individual maps. For example, a map may include a plurality of keyframes, each of which may have a frame descriptor as described above. Amax pool unit may analyze the frame descriptors of the map's key framesand combines the frame descriptors into a unique map descriptor for themap.

Further, it should be appreciated that other architectures may be usedfor processing as described above. For example, separate neural networksare described for generating DSF descriptors and frame descriptors. Suchan approach is computationally efficient. However, in some embodiments,the frame descriptors may be generated from selected feature points,without first generating DSF descriptors.

Ranking and Merging Maps

Described herein are methods and apparatus for ranking a plurality ofenvironment maps in an X Reality (XR) system as a precursor to furtherprocessing, such as merging maps or localizing a device relative to amap. Map merging may enable maps representing overlapping portions ofthe physical world to be combined to represent a larger area. Rankingmaps may enable efficiently performing techniques as described herein,including map merging or localization, both of which may involveselecting a map from a set of maps based on similarity. In someembodiments, for example, a set of canonical maps formatted in a waythat they may be accessed by any of a number of XR devices may bemaintained by the system. These canonical maps may be formed by mergingselected tracking maps from those devices with other tracking maps orpreviously stored canonical maps.

The canonical maps may be ranked, for example, for use in selecting oneor more canonical maps to merge with a new tracking map and/or to selectone or more canonical maps from the set to use within a device. Theranking may indicate canonical maps that have regions similar to aregion of the tracking map such that, upon attempting to merge thetracking map into the canonical map, it is likely that there will be acorrespondence between a portion of the tracking map and a portion ofthe canonical map. Such a correspondence may be a precursor to furtherprocessing in which the tracking map is aligned with the canonical mapsuch that it can be merged into the canonical map.

In some embodiments, a tracking map may be merged with a tile or otherdefined area of a canonical map so as to limit the amount of processingrequired to merge a tracking map with a canonical map. Operating onareas of a canonical map, particularly for canonical maps that representa relatively large area such as multiple rooms in a building, mayrequire less processing than operations on an entire map. In thoseembodiments, the map ranking or other selection pre-processing, mayidentify one or more areas of previously stored canonical maps toattempt to merge.

For localization, the information about the location of a portabledevice is compared to information in a canonical map. A region ofcorrespondence between the information from the local device and acanonical map may be more quickly identified if a set of candidate areasin a set of canonical maps is identified by ranking the canonical mapsin the set.

The inventors have recognized and appreciated that an XR system couldprovide an enhanced XR experience to multiple users sharing a sameworld, comprising real and/or virtual content, by enabling efficientsharing of environment maps of the real/physical world collected bymultiple users, whether those users are present in the world at the sameor different times. However, there are significant challenges inproviding such a system. Such a system may store multiple maps generatedby multiple users and/or the system may store multiple maps generated atdifferent times. For operations that might be performed with apreviously generated map, such as localization or map merge, forexample, substantial processing may be required to identify a relevantenvironment map of a same world (e.g., same real-world location) fromall the environment maps collected in an XR system.

In some systems, there may be a large number of environment maps fromwhich to make a selection of a map. The inventors have recognized andappreciated techniques to quickly and accurately rank the relevance ofenvironment maps out of all possible environment maps, such as theuniverse of all canonical maps 120 in FIG. 28 , for example. Ahigh-ranking map, or a small set of high-ranking maps, may then beselected for further processing. That further processing may includedetermining the location of a user device with respect to a selectedmap, or rendering virtual objects on a user display realisticallyinteracting with the physical world around the user or merging map datacollected by that user device with stored maps to create larger or moreaccurate maps.

In some embodiments, a stored map that is relevant to a task for a userat a location in the physical world may be identified by filteringstored maps based on multiple criteria. Those criteria may indicatecomparisons of a tracking map or other location information generated bythe wearable device of the user in the location to candidate environmentmaps stored in a database. The comparisons may be performed based onmetadata associated with the maps, such as a Wi-Fi fingerprint detectedby the device generating the map and/or set of BSSIDs to which thedevice was connected while forming the map. Geolocation information,such as GPS data, may alternatively or additionally be used in selectingone or more candidate environment maps. A priori information may also beused in the selection of candidate maps. For example, if a device'slocation has been recently determined with respect to a canonical map,canonical maps representing the prior determined location, and adjacentlocations, may be selected.

The comparisons may be performed based on compressed or uncompressedcontent of the map. Comparisons based on a compressed representation maybe performed, for example, by comparison of vectors computed from mapcontent. Comparisons based on un-compressed representations may beperformed, for example, by localizing the tracking map within the storedmap, or vice versa. Localization may be performed, for example, bymatching one or more sets of features representing a portion of one mapwith sets of features in another map. Multiple comparisons may beperformed in an order based on computation time needed to reduce thenumber of candidate maps for consideration, with comparisons involvingless computation being performed earlier in the order than othercomparisons requiring more computation.

In some embodiments, the comparison may be based on a portion of thetracking map, and the portion of the tracking may be different dependingon the process for which an environment map is being selected. Forexample, for localization, candidate maps may be selected based on thepersistent pose in the tracking map that is closest to the user at thetime localization is to be performed. In contrast, when selectingcandidate maps for a map merge operation, candidate maps may be selectedbased on similarity between any one or more persistent poses in thetracking map and the canonical maps. Regardless of what portions of twomaps are compared, finding matching portions may entail substantialprocess associated with finding sets of features in the maps that likelycorrespond to the same location in the physical world.

FIG. 26 depicts an AR system 800 configured to rank one or moreenvironment maps, according to some embodiments. In this example, theranking is being done as a precursor to a merge operation. The AR systemmay include a passable world model 802 of an AR device. Information topopulate the passable world model 802 may come from sensors on the ARdevice, which may include computer executable instructions stored in aprocessor 804 (e.g., a local data processing module 570 in FIG. 4 ),which may perform some or all of the processing to convert sensor datainto a map. Such a map may be a tracking map, as it can be built assensor data is collected as the AR device operates in a region. Alongwith that tracking map, area attributes, which may be formatted asmetadata of the map, may be supplied so as to indicate the area that thetracking map represents. These area attributes may be a geographiclocation identifier, such as coordinates presented as latitude andlongitude or an ID used by the AR system to represent a location.Alternatively, or additionally, the area attributes may be measuredcharacteristics that have a high likelihood of being unique for thatarea. The area attributes, for example, may be derived from parametersof wireless networks detected in the area. In some embodiments, the areaattribute may be associated with a unique address of an access-point theAR system is nearby and/or connected to. For example, the area attributemay be associated with a MAC address or basic service set identifiers(BSSIDs) of a 5G base station/router, a Wi-Fi router, and the like.

The attributes may be attached to the map itself or to locationsrepresented in the map. For example, an attribute of a tracking map maybe associated with a persistent pose in the map. For a canonical map,the attributes may be associated with a persistent coordinate frame or atile or other area of the map.

In the example of FIG. 26 , the tracking maps may be merged with othermaps of the environment. A map rank portion 806 receives tracking mapsfrom the device PW 802 and communicates with a map database 808 toselect and rank environment maps from the map database 808. Higherranked, selected maps are sent to a map merge portion 810.

The map merge portion 810 may perform merge processing on the maps sentfrom the map rank portion 806. Merge processing may entail merging thetracking map with some or all of the ranked maps and transmitting thenew, merged maps to a passable world model 812. The map merge portionmay merge maps by identifying maps that depict overlapping portions ofthe physical world. Those overlapping portions may be aligned such thatinformation in both maps may be aggregated into a final map.

In some embodiments, the overlapping portions may be identified by firstidentifying a set of features in a canonical map that likely correspondwith a set of features associated with a persistent pose in a trackingmap. The set of features in the canonical map may be a set of featuresdefining a persistent coordinate frame. However, there is no requirementthat the set of features be associated with a single persistent locationin either the canonical map or the tracking map. In some embodiments,processing may be simplified by identifying correspondences between setsof features to which attributes have been assigned, such that values ofthose attributes may be compared to select sets of features for furtherprocessing.

Once a set of candidate maps, or in some embodiments, candidate areas ofmaps, have been identified, further steps may reduce the set ofcandidates, and may ultimately lead to the identification of a matchingmap. One such step may be computing a transformation of the set offeature points in the tracking map to align with the candidate set offeatures in the canonical map. This transformation may be applied to theentire tracking map, enabling overlapping portions of the tracking mapand the canonical map to be identified. Correspondence, above athreshold, between features in the overlapping portions may indicate astrong likelihood that the tracking map has been registered with thecanonical map. If the correspondence is below the threshold, othercandidate sets of features in the tracking map and/or canonical map maybe processed in an attempt to find matching regions of the maps. When asufficiently large correspondence is found, the tracking map may beregarded as being localized with respect to the canonical map, with thetransformation leading to the large correspondence indicating thelocation of the tracking map relative to the canonical map.

Similar processing may be performed to merge canonical maps with othercanonical maps as well as with tracking maps. Merging of canonical mapmay be performed from time to time to identify scenarios in whichcanonical maps have been extended through repeated merging of trackingmaps such that multiple maps represent an overlapping region of thephysical world. Regardless of the type of maps that are merged, whenthere is overlap between the maps being merged, merging may entailaggregating data from both maps. The aggregation may entail extendingone map with information from another map. Alternatively, oradditionally, aggregation may entail adjusting the representation of thephysical world in one map, based on information in another map. A latermap, for example, may reveal that objects giving rise to feature pointshave moved, such that the map may be updated based on later information.Alternatively, two maps may characterize the same region with differentfeature points and aggregating may entail selecting a set of featurepoints from the two maps to better represent that region.

Regardless of the specific processing that occurs in the mergingprocess, in some embodiments, persistent locations, such as persistentposes or PCFs, from all maps that are merged may be retained, such thatapplications positioning content with respect to them may continue to doso. In some embodiments, merging of maps may result in redundantpersistent poses, and some of the persistent poses may be deleted. Whena PCF is associated with a persistent pose that is to be deleted,merging maps may entail modifying the PCF to be associated with apersistent pose remaining in the map after merging.

In some embodiments, as maps are extended and or updated, they may berefined. Refinement may entail computation to reduce internalinconsistency between feature points that likely represent the sameobject in the physical world. Inconsistency may result from inaccuraciesin the poses associated with key frames supplying feature points thatrepresent the same objects in the physical world. Such inconsistency mayresult, for example, from an XR device computing poses relative to atracking map, which in turn is built based on estimating poses, suchthat errors in pose estimation accumulate, creating a “drift” in poseaccuracy over time. By performing a bundle adjustment or other operationto reduce inconsistencies of the feature points from multiple keyframes, the map may be refined.

Upon a refinement, the location of a persistent point relative to theorigin of a map may change. Accordingly, the transformation associatedwith that persistent point, such as a persistent pose or a PCF, maychange. In some embodiments, the XR system, in connection with maprefinement (whether as part of a merge operation or performed for otherreasons) may re-compute transformations associated with any persistentpoints that have changed. These transformations might be pushed from acomponent computing the transformations to a component using thetransformation such that any uses of the transformations may be based onthe updated location of the persistent points.

Merging may also entail assigning location metadata to locations in themerged map based on attributes associated with locations in the maps tobeing merged. For example, the attributes of a canonical map may bederived from the attributes of the tracking map or maps used to form anarea of the canonical map. In scenarios in which a persistent coordinateframe of a canonical map is defined based on a persistent pose in atracking map that was merged into the canonical map, the persistentcoordinate frame may be assigned the same attributes as the persistentpose. Where a persistent coordinate frame is derived from one or morepersistent poses from one or more tracking maps, the attributes assignedto the persistent coordinate frame may be an aggregation of theattributes of the persistent poses. The manner in which attributes areaggregated may vary based on the type of attribute. Geo-locationattributes may be aggregated by interpolating a value of the attributefor the location of the persistent coordinate frame from thegeo-location information associated with the persistent poses. For otherattributes, the values may be aggregated by considering all to apply tothe persistent coordinate frame. Similar logic may be applied to deriveattributes for tiles or other areas of a map.

In scenarios in which a tracking map submitted for merging does not havesufficient correlation to any previously stored canonical map, thesystem may create a new canonical map based on that tracking map. Insome embodiments, the tracking map may be promoted to a canonical map.In this way, the region of the physical world represented by the set ofcanonical maps may grow as user devices submit tracking maps formerging.

Passable world model 812 may be a cloud model, which may be shared bymultiple AR devices. Passable world model 812 may store or otherwisehave access to the environment maps in map database 808. In someembodiments, when a previously computed environment map is updated, theprior version of that map may be deleted so as to remove out of datemaps from the database. In some embodiments, when a previously computedenvironment map is updated, the prior version of that map may bearchived enabling retrieving/viewing prior versions of an environment.In some embodiments, permissions may be set such that only AR systemshaving certain read/write access may trigger prior versions of mapsbeing deleted/archived.

These environment maps created from tracking maps supplied by one ormore AR devices/systems may be accessed by AR devices in the AR system.The map rank portion 806 also may be used in supplying environment mapsto an AR device. The AR device may send a message requesting anenvironment map for its current location, and map rank portion 806 maybe used to select and rank environment maps relevant to the requestingdevice.

In some embodiments, the AR system 800 may include a downsample portion814 configured to receive the merged maps from the cloud PW 812. Thereceived merged maps from the cloud PW 812 may be in a storage formatfor the cloud, which may include high resolution information, such as alarge number of PCFs per square meter or multiple image frames or alarge set of feature points associated with a PCF. The downsampleportion 814 may be configured to downsample the cloud format maps to aformat suitable for storage on AR devices. The device format maps mayhave less data, such as fewer PCFs or less data stored for each PCF toaccommodate the limited local computing power and storage space of ARdevices.

FIG. 27 is a simplified block diagram illustrating a plurality ofcanonical maps 120 that may be stored in a remote storage medium, forexample, a cloud. Each canonical map 120 may include a pluralityattributes serving as canonical map identifiers indicating the canonicalmap's location within a physical space, such as somewhere on the planetearth. These canonical map identifiers may include one or more of thefollowing identifiers: area identifiers represented by a range oflongitudes and latitudes, frame descriptors (e.g., global feature string316 in FIG. 21 ), Wi-Fi fingerprints, feature descriptors (e.g., featuredescriptors 310 in FIG. 21 ), and device identities indicating one ormore devices that contributed to the map. In searching for acorrespondence between maps, these attributes may be used to definewhich maps are compared and/or which portions or maps are compared.

Though each of the elements in FIG. 27 may be regarded as a separatemap, in some embodiments, processing may be performed on tiles or otherareas of canonical maps. Canonical maps 120, for example, may eachrepresent an area of a larger map. In those embodiments, attributes maybe assigned to areas instead of or in addition to the entire map.Accordingly, discussions herein of selection of a map may alternativelyor additionally apply to selecting a segment of a map, such as one ormore tiles.

In the illustrated example, the canonical maps 120 are disposedgeographically in a two-dimensional pattern as they may exist on asurface of the earth. The canonical maps 120 may be uniquelyidentifiable by corresponding longitudes and latitudes because anycanonical maps that have overlapping longitudes and latitudes may bemerged into a new canonical map.

FIG. 28 is a schematic diagram illustrating a method of selectingcanonical maps, which may be used for localizing a new tracking map toone or more canonical maps, according to some embodiment. Suchprocessing may be used in identifying candidate maps for merging or maybe used to localize a user device with respect to a canonical map. Themethod may start from accessing (Act 120) a universe of canonical maps120, which may be stored, as an example, in a database in a passableworld (e.g., the passable world module 538). The universe of canonicalmaps may include canonical maps from all previously visited locations.An XR system may filter the universe of all canonical maps to a smallsubset or just a single map. The selected set may be sent to a userdevice for further processing on the device. Alternatively, oradditionally, some or all of the further processing may be performed inthe cloud, and results of that processing may be sent to the user deviceand/or stored in the cloud, as is the case for merging maps.

The method may include filtering (Act 300) the universe of canonicalmaps. In some embodiments, the Act 300 may select at least one matchingcanonical map 120 covering longitude and latitude that include thatlongitude and latitude of the position identifier received from an XRdevice, as long as at least one map exists at that longitude andlatitude. In some embodiments, the Act 300 may select at least oneneighboring canonical map covering longitude and latitude that areadjacent the matching canonical map. In some embodiments, the Act 300may select a plurality of matching canonical maps and a plurality ofneighboring canonical maps. The Act 300 may, for example, reduce thenumber of canonical maps approximately ten times, for example, fromthousands to hundreds to form a first filtered selection. Alternativelyor additionally, criteria other than latitude and longitude may be usedto identify neighboring maps. An XR device, for example, may havepreviously localized with a canonical map in the set as part of the samesession. A cloud service may retain information about the XR device,including maps previously localized to. In this example, the mapsselected at Act 300 may include those that cover an area adjacent to themap to which the XR device localized to.

The method may include filtering (Act 302) the first filtered selectionof canonical maps based on Wi-Fi fingerprints. The Act 302 may determinea latitude and longitude based on a Wi-Fi fingerprint received as partof the position identifier from an XR device. The Act 302 may comparethe latitude and longitude from the Wi-Fi fingerprint with latitude andlongitude of the canonical maps 120 to determine one or more canonicalmaps that form a second filtered selection. The Act 302 may reduce thenumber of canonical maps approximately ten times, for example, fromhundreds to tens of canonical maps (e.g., 50) that form a secondselection. For example, a first filtered selection may include 130canonical maps and the second filtered selection may include 50 of the130 canonical maps and may not include the other 80 of the 130 canonicalmaps.

The method may include filtering (Act 304) the second filtered selectionof canonical maps based on key frames. The Act 304 may compare datarepresenting an image captured by an XR device with data representingthe canonical maps 120. In some embodiments, the data representing theimage and/or maps may include feature descriptors (e.g., DSF descriptorsin FIG. 25 ) and/or global feature strings (e.g., 316 in FIG. 21 ). TheAct 304 may provide a third filtered selection of canonical maps. Insome embodiments, the output of Act 304 may only be five of the 50canonical maps identified following the second filtered selection, forexample. The map transmitter 122 then transmits the one or morecanonical maps based on the third filtered selection to the viewingdevice. The Act 304 may reduce the number of canonical maps forapproximately ten times, for example, from tens to single digits ofcanonical maps (e.g., 5) that form a third selection. In someembodiments, an XR device may receive canonical maps in the thirdfiltered selection, and attempt to localize into the received canonicalmaps.

For example, the Act 304 may filter the canonical maps 120 based on theglobal feature strings 316 of the canonical maps 120 and the globalfeature string 316 that is based on an image that is captured by theviewing device (e.g., an image that may be part of the local trackingmap for a user). Each one of the canonical maps 120 in FIG. 27 thus hasone or more global feature strings 316 associated therewith. In someembodiments, the global feature strings 316 may be acquired when an XRdevice submits images or feature details to the cloud and the cloudprocesses the image or feature details to generate global featurestrings 316 for the canonical maps 120.

In some embodiments, the cloud may receive feature details of alive/new/current image captured by a viewing device, and the cloud maygenerate a global feature string 316 for the live image. The cloud maythen filter the canonical maps 120 based on the live global featurestring 316. In some embodiments, the global feature string may begenerated on the local viewing device. In some embodiments, the globalfeature string may be generated remotely, for example on the cloud. Insome embodiments, a cloud may transmit the filtered canonical maps to anXR device together with the global feature strings 316 associated withthe filtered canonical maps. In some embodiments, when the viewingdevice localizes its tracking map to the canonical map, it may do so bymatching the global feature strings 316 of the local tracking map withthe global feature strings of the canonical map.

It should be appreciated that an operation of an XR device may notperform all of the Acts (300, 302, 304). For example, if a universe ofcanonical maps is relatively small (e.g., 500 maps), an XR deviceattempting to localize may filter the universe of canonical maps basedon Wi-Fi fingerprints (e.g., Act 302) and Key Frame (e.g., Act 304), butomit filtering based on areas (e.g., Act 300). Moreover, it is notnecessary that maps in their entireties be compared. In someembodiments, for example, a comparison of two maps may result inidentifying common persistent points, such as persistent poses or PCFsthat appear in both the new map the selected map from the universe ofmaps. In that case, descriptors may be associated with persistentpoints, and those descriptors may be compared.

FIG. 29 is flow chart illustrating a method 900 of selecting one or moreranked environment maps, according to some embodiments. In theillustrated embodiment, the ranking is performed for a user's AR devicethat is creating a tracking map. Accordingly, the tracking map isavailable for use in ranking environment maps. In embodiments in whichthe tracking map is not available, some or all of portions of theselection and ranking of environment maps that do not expressly rely onthe tracking map may be used.

The method 900 may start at Act 902, where a set of maps from a databaseof environment maps (which may be formatted as canonical maps) that arein the neighborhood of the location where the tracking map was formedmay be accessed and then filtered for ranking. Additionally, at Act 902,at least one area attribute for the area in which the user's AR deviceis operating is determined. In scenarios in which the user's AR deviceis constructing a tracking map, the area attributes may correspond tothe area over which the tracking map was created. As a specific example,the area attributes may be computed based on received signals fromaccess points to computer networks while the AR device was computing thetracking map.

FIG. 30 depicts an exemplary map rank portion 806 of the AR system 800,according to some embodiments. The map rank portion 806 may be executingin a cloud computing environment, as it may include portions executingon AR devices and portions executing on a remote computing system suchas a cloud. The map rank portion 806 may be configured to perform atleast a portion of the method 900.

FIG. 31A depicts an example of area attributes AA1-AA8 of a tracking map(TM) 1102 and environment maps CM1-CM4 in a database, according to someembodiments. As illustrated, an environment map may be associated tomultiple area attributes. The area attributes AA1-AA8 may includeparameters of wireless networks detected by the AR device computing thetracking map 1102, for example, basic service set identifiers (BSSIDs)of networks to which the AR device are connected and/or the strength ofthe received signals of the access points to the wireless networksthrough, for example, a network tower 1104. The parameters of thewireless networks may comply with protocols including Wi-Fi and 5G NR.In the example illustrated in FIG. 32 , the area attributes are afingerprint of the area in which the user AR device collected sensordata to form the tracking map.

FIG. 31B depicts an example of the determined geographic location 1106of the tracking map 1102, according to some embodiments. In theillustrated example, the determined geographic location 1106 includes acentroid point 1110 and an area 1108 circling around the centroid point.It should be appreciated that the determination of a geographic locationof the present application is not limited to the illustrated format. Adetermined geographic location may have any suitable formats including,for example, different area shapes. In this example, the geographiclocation is determined from area attributes using a database relatingarea attributes to geographic locations. Databases are commerciallyavailable, for example, databases that relate Wi-Fi fingerprints tolocations expressed as latitude and longitude and may be used for thisoperation.

In the embodiment of FIG. 29 , a map database, containing environmentmaps may also include location data for those maps, including latitudeand longitude covered by the maps. Processing at Act 902 may entailselecting from that database a set of environment maps that covers thesame latitude and longitude determined for the area attributes of thetracking map.

Act 904 is a first filtering of the set of environment maps accessed inAct 902. In Act 902, environment maps are retained in the set based onproximity to the geo-location of the tracking map. This filtering stepmay be performed by comparing the latitude and longitude associated withthe tracking map and the environment maps in the set.

FIG. 32 depicts an example of Act 904, according to some embodiments.Each area attribute may have a corresponding geographic location 1202.The set of environment maps may include the environment maps with atleast one area attribute that has a geographic location overlapping withthe determined geographic location of the tracking map. In theillustrated example, the set of identified environment maps includesenvironment maps CM1, CM2, and CM4, each of which has at least one areaattribute that has a geographic location overlapping with the determinedgeographic location of the tracking map 1102. The environment map CM3associated with the area attribute AA6 is not included in the setbecause it is outside the determined geographic location of the trackingmap.

Other filtering steps may also be performed on the set of environmentmaps to reduce/rank the number of environment maps in the set that isultimately processed (such as for map merge or to provide passable worldinformation to a user device). The method 900 may include filtering (Act906) the set of environment maps based on similarity of one or moreidentifiers of network access points associated with the tracking mapand the environment maps of the set of environment maps. During theformation of a map, a device collecting sensor data to generate the mapmay be connected to a network through a network access point, such asthrough Wi-Fi or similar wireless communication protocol. The accesspoints may be identified by BSSID. The user device may connect tomultiple different access points as it moves through an area collectingdata to form a map. Likewise, when multiple devices supply informationto form a map, the devices may have connected through different accesspoints, so there may be multiple access points used in forming the mapfor that reason too. Accordingly, there may be multiple access pointsassociated with a map, and the set of access points may be an indicationof location of the map. Strength of signals from an access point, whichmay be reflected as an RSSI value, may provide further geographicinformation. In some embodiments, a list of BSSID and RSSI values mayform the area attribute for a map.

In some embodiments, filtering the set of environment maps based onsimilarity of the one or more identifiers of the network access pointsmay include retaining in the set of environment maps environment mapswith the highest Jaccard similarity to the at least one area attributeof the tracking map based on the one or more identifiers of networkaccess points. FIG. 33 depicts an example of Act 906, according to someembodiments. In the illustrated example, a network identifier associatedwith the area attribute AA7 may be determined as the identifier for thetracking map 1102. The set of environment maps after Act 906 includesenvironment map CM2, which may have area attributes within higherJaccard similarity to AA7, and environment map CM4, which also includethe area attributes AA7. The environment map CM1 is not included in theset because it has the lowest Jaccard similarity to AA7.

Processing at Acts 902-906 may be performed based on metadata associatedwith maps and without actually accessing the content of the maps storedin a map database. Other processing may involve accessing the content ofthe maps. Act 908 indicates accessing the environment maps remaining inthe subset after filtering based on metadata. It should be appreciatedthat this act may be performed either earlier or later in the process,if subsequent operations can be performed with accessed content.

The method 900 may include filtering (Act 910) the set of environmentmaps based on similarity of metrics representing content of the trackingmap and the environment maps of the set of environment maps. The metricsrepresenting content of the tracking map and the environment maps mayinclude vectors of values computed from the contents of the maps. Forexample, the Deep Key Frame descriptor, as described above, computed forone or more key frames used in forming a map may provide a metric forcomparison of maps, or portions of maps. The metrics may be computedfrom the maps retrieved at Act 908 or may be pre-computed and stored asmetadata associated with those maps. In some embodiments, filtering theset of environment maps based on similarity of metrics representingcontent of the tracking map and the environment maps of the set ofenvironment maps, may include retaining in the set of environment mapsenvironment maps with the smallest vector distance between a vector ofcharacteristics of the tracking map and vectors representing environmentmaps in the set of environment maps.

The method 900 may include further filtering (Act 912) the set ofenvironment maps based on degree of match between a portion of thetracking map and portions of the environment maps of the set ofenvironment maps. The degree of match may be determined as a part of alocalization process. As a non-limiting example, localization may beperformed by identifying critical points in the tracking map and theenvironment map that are sufficiently similar as they could representthe same portion of the physical world. In some embodiments, thecritical points may be features, feature descriptors, key frames/keyrigs, persistent poses, and/or PCFs. The set of critical points in thetracking map might then be aligned to produce a best fit with the set ofcritical points in the environment map. A mean square distance betweenthe corresponding critical points might be computed and, if below athreshold for a particular region of the tracking map, used as anindication that the tracking map and the environment map represent thesame region of the physical world.

In some embodiments, filtering the set of environment maps based ondegree of match between a portion of the tracking map and portions ofthe environment maps of the set of environment maps may includecomputing a volume of a physical world represented by the tracking mapthat is also represented in an environment map of the set of environmentmaps, and retaining in the set of environment maps environment maps witha larger computed volume than environment maps filtered out of the set.FIG. 34 depicts an example of Act 912, according to some embodiments. Inthe illustrated example, the set of environment maps after Act 912includes environment map CM4, which has an area 1402 matched with anarea of the tracking map 1102. The environment map CM1 is not includedin the set because it has no area matched with an area of the trackingmap 1102.

In some embodiments, the set of environment maps may be filtered in theorder of Act 906, Act 910, and Act 912. In some embodiments, the set ofenvironment maps may be filtered based on Act 906, Act 910, and Act 912,which may be performed in an order based on processing required toperform the filtering, from lowest to highest. The method 900 mayinclude loading (Act 914) the set of environment maps and data.

In the illustrated example, a user database stores area identitiesindicating areas that AR devices were used in. The area identities maybe area attributes, which may include parameters of wireless networksdetected by the AR devices when in use. A map database may storemultiple environment maps constructed from data supplied by the ARdevices and associated metadata. The associated metadata may includearea identities derived from the area identities of the AR devices thatsupplied data from which the environment maps were constructed. An ARdevice may send a message to a PW module indicating a new tracking mapis created or being created. The PW module may compute area identifiersfor the AR device and updates the user database based on the receivedparameters and/or the computed area identifiers. The PW module may alsodetermine area identifiers associated with the AR device requesting theenvironment maps, identify sets of environment maps from the mapdatabase based on the area identifiers, filter the sets of environmentmaps, and transmit the filtered sets of environment maps to the ARdevices. In some embodiments, the PW module may filter the sets ofenvironment maps based on one or more criteria including, for example, ageographic location of the tracking map, similarity of one or moreidentifiers of network access points associated with the tracking mapand the environment maps of the set of environment maps, similarity ofmetrics representing contents of the tracking map and the environmentmaps of the set of environment maps, and degree of match between aportion of the tracking map and portions of the environment maps of theset of environment maps.

Having thus described several aspects of some embodiments, it is to beappreciated that various alterations, modifications, and improvementswill readily occur to those skilled in the art. As one example,embodiments are described in connection with an augmented (AR)environment. It should be appreciated that some or all of the techniquesdescribed herein may be applied in an MR environment or more generallyin other XR environments, and in VR environments.

As another example, embodiments are described in connection withdevices, such as wearable devices. It should be appreciated that some orall of the techniques described herein may be implemented via networks(such as cloud), discrete applications, and/or any suitable combinationsof devices, networks, and discrete applications.

Further, FIG. 29 provides examples of criteria that may be used tofilter candidate maps to yield a set of high-ranking maps. Othercriteria may be used instead of or in addition to the describedcriteria. For example, if multiple candidate maps have similar values ofa metric used for filtering out fewer desirable maps, characteristics ofthe candidate maps may be used to determine which maps are retained ascandidate maps or filtered out. For example, larger or more densecandidate maps may be prioritized over smaller candidate maps. In someembodiments, FIGS. 27-28 may describe all or part of the systems andmethods described in FIGS. 29-34 .

FIGS. 35 and 36 are schematic diagrams illustrating an XR systemconfigured to rank and merge a plurality of environment maps, accordingto some embodiments. In some embodiments, a passable world (PW) maydetermine when to trigger ranking and/or merging the maps. In someembodiments, determining a map to be used may be based at least partlyon deep key frames described above in relation to FIGS. 21-25 ,according to some embodiments.

FIG. 37 is a block diagram illustrating a method 3700 of creatingenvironment maps of a physical world, according to some embodiments. Themethod 3700 may start from localizing (Act 3702) a tracking map capturedby an XR device worn by a user to a group of canonical maps (e.g.,canonical maps selected by the method of FIG. 28 and/or the method 900of FIG. 29 ). The Act 3702 may include localizing keyrigs of thetracking map into the group of canonical maps. The localization resultof each keyrig may include the keyrig's localized pose and a set of2D-to-3D feature correspondences.

In some embodiments, the method 3700 may include splitting (Act 3704) atracking map into connected components, which may enable merging mapsrobustly by merging connected pieces. Each connected component mayinclude keyrigs that are within a predetermined distance. The method3700 may include merging (Act 3706) the connected components that arelarger than a predetermined threshold into one or more canonical maps,and removing the merged connected components from the tracking map.

In some embodiments, the method 3700 may include merging (Act 3708)canonical maps of the group that are merged with the same connectedcomponents of the tracking map. In some embodiments, the method 3700 mayinclude promoting (Act 3710) the remaining connected components of thetracking map that has not been merged with any canonical maps to be acanonical map. In some embodiments, the method 3700 may include merging(Act 3712) persistent poses and/or PCFs of the tracking maps and thecanonical maps that are merged with at least one connected component ofthe tracking map. In some embodiments, the method 3700 may includefinalizing (Act 3714) the canonical maps by, for example, fusing mappoints and pruning redundant keyrigs.

FIGS. 38A and 38B illustrate an environment map 3800 created by updatinga canonical map 700, which may be promoted from the tracking map 700(FIG. 7 ) with a new tracking map, according to some embodiments. Asillustrated and described with respect to FIG. 7 , the canonical map 700may provide a floor plan 706 of reconstructed physical objects in acorresponding physical world, represented by points 702. In someembodiments, a map point 702 may represent a feature of a physicalobject that may include multiple features. A new tracking map may becaptured about the physical world and uploaded to a cloud to merge withthe map 700. The new tracking map may include map points 3802, andkeyrigs 3804, 3806. In the illustrated example, keyrigs 3804 representkeyrigs that are successfully localized to the canonical map by, forexample, establishing a correspondence with a keyrig 704 of the map 700(as illustrated in FIG. 38B). On the other hand, keyrigs 3806 representkeyrigs that have not been localized to the map 700. Keyrigs 3806 may bepromoted to a separate canonical map in some embodiments.

FIGS. 39A to 39F are schematic diagrams illustrating an example of acloud-based persistent coordinate system providing a shared experiencefor users in the same physical space. FIG. 39A shows that a canonicalmap 4814, for example, from a cloud, is received by the XR devices wornby the users 4802A and 4802B of FIGS. 20A-20C. The canonical map 4814may have a canonical coordinate frame 4806C. The canonical map 4814 mayhave a PCF 4810C with a plurality of associated PPs (e.g., 4818A, 4818Bin FIG. 39C).

FIG. 39B shows that the XR devices established relationships betweentheir respective world coordinate system 4806A, 4806B with the canonicalcoordinate frame 4806C. This may be done, for example, by localizing tothe canonical map 4814 on the respective devices. Localizing thetracking map to the canonical map may result, for each device, atransformation between its local world coordinate system and thecoordinate system of the canonical map.

FIG. 39C shows that, as a result of localization, a transformation canbe computed (e.g., transformation 4816A, 4816B) between a local PCF(e.g., PCFs 4810A, 4810B) on the respective device to a respectivepersistent pose (e.g., PPs 4818A, 4818B) on the canonical map. Withthese transformations, each device may use its local PCFs, which can bedetected locally on the device by processing images detected withsensors on the device, to determine where with respect to the localdevice to display virtual content attached to the PPs 4818A, 4818B orother persistent points of the canonical map. Such an approach mayaccurately position virtual content with respect to each user and mayenable each user to have the same experience of the virtual content inthe physical space.

FIG. 39D shows a persistent pose snapshot from the canonical map to thelocal tracking maps. As can be seen, the local tracking maps areconnected to one another via the persistent poses. FIG. 39E shows thatthe PCF 4810A on the device worn by the user 4802A is accessible in thedevice worn by the user 4802B through PPs 4818A. FIG. 39F shows that thetracking maps 4804A, 4804B and the canonical 4814 may merge. In someembodiments, some PCFs may be removed as a result of merging. In theillustrated example, the merged map includes the PCF 4810C of thecanonical map 4814 but not the PCFs 4810A, 48108 of the tracking maps4804A, 4804B. The PPs previously associated with the PCFs 4810A, 4810Bmay be associated with the PCF 4810C after the maps merge.

EXAMPLES

FIGS. 40 and 41 illustrate an example of using a tracking map by thefirst XR device 12.1 of FIG. 9 . FIG. 40 is a two-dimensionalrepresentation of a three-dimensional first local tracking map (Map 1),which may be generated by the first XR device of FIG. 9 , according tosome embodiments. FIG. 41 is a block diagram illustrating uploading Map1 from the first XR device to the server of FIG. 9 , according to someembodiments.

FIG. 40 illustrates Map 1 and virtual content (Content123 andContent456) on the first XR device 12.1. Map 1 has an origin (Origin 1).Map 1 includes a number of PCFs (PCF a to PCF d). From the perspectiveof the first XR device 12.1, PCF a, by way of example, is located at theorigin of Map 1 and has X, Y, and Z coordinates of (0,0,0) and PCF b hasX, Y, and Z coordinates (−1,0,0). Content123 is associated with PCF a.In the present example, Content123 has an X, Y, and Z relationshiprelative to PCF a of (1,0,0). Content456 has a relationship relative toPCF b. In the present example, Content456 has an X, Y, and Zrelationship of (1,0,0) relative to PCF b.

In FIG. 41 , the first XR device 12.1 uploads Map 1 to the server 20. Inthis example, as the server stores no canonical map for the same regionof the physical world represented by the tracking map, and the trackingmap is stored as an initial canonical map. The server 20 now has acanonical map based on Map 1. The first XR device 12.1 has a canonicalmap that is empty at this stage. The server 20, for purposes ofdiscussion, and in some embodiments, includes no other maps other thanMap 1. No maps are stored on the second XR device 12.2.

The first XR device 12.1 also transmits its Wi-Fi signature data to theserver 20. The server 20 may use the Wi-Fi signature data to determine arough location of the first XR device 12.1 based on intelligencegathered from other devices that have, in the past, connected to theserver 20 or other servers together with the GPS locations of such otherdevices that have been recorded. The first XR device 12.1 may now endthe first session (See FIG. 8 ) and may disconnect from the server 20.

FIG. 42 is a schematic diagram illustrating the XR system of FIG. 16 ,showing the second user 14.2 has initiated a second session using asecond XR device of the XR system after the first user 14.1 hasterminated a first session, according to some embodiments. FIG. 43A is ablock diagram showing the initiation of a second session by a seconduser 14.2. The first user 14.1 is shown in phantom lines because thefirst session by the first user 14.1 has ended. The second XR device12.2 begins to record objects. Various systems with varying degrees ofgranulation may be used by the server 20 to determine that the secondsession by the second XR device 12.2 is in the same vicinity of thefirst session by the first XR device 12.1. For example, Wi-Fi signaturedata, global positioning system (GPS) positioning data, GPS data basedon Wi-Fi signature data, or any other data that indicates a location maybe included in the first and second XR devices 12.1 and 12.2 to recordtheir locations. Alternatively, the PCFs that are identified by thesecond XR device 12.2 may show a similarity to the PCFs of Map 1.

As shown in FIG. 43B, the second XR device boots up and begins tocollect data, such as images 1110 from one or more cameras 44, 46. Asshown in FIG. 14 , in some embodiments, an XR device (e.g., the secondXR device 12.2) may collect one or more images 1110 and perform imageprocessing to extract one or more features/interest points 1120. Eachfeature may be converted to a descriptor 1130. In some embodiments, thedescriptors 1130 may be used to describe a key frame 1140, which mayhave the position and direction of the associated image attached. One ormore key frames 1140 may correspond to a single persistent pose 1150,which may be automatically generated after a threshold distance from theprevious persistent pose 1150, e.g., 3 meters. One or more persistentposes 1150 may correspond to a single PCF 1160, which may beautomatically generated after a predetermined distance, e.g., every 5meters. Over time as the user continues to move around the user'senvironment, and the XR device continues to collect more data, such asimages 1110, additional PCFs (e.g., PCF 3 and PCF 4, 5) may be created.One or more applications 1180 may run on the XR device and providevirtual content 1170 to the XR device for presentation to the user. Thevirtual content may have an associated content coordinate frame whichmay be placed relative to one or more PCFs. As shown in FIG. 43B, thesecond XR device 12.2 creates three PCFs. In some embodiments, thesecond XR device 12.2 may try to localize into one or more canonicalmaps stored on the server 20.

In some embodiments, as shown in FIG. 43C, the second XR device 12.2 maydownload the canonical map 120 from the server 20. Map 1 on the secondXR device 12.2 includes PCFs a to d and Origin 1. In some embodiments,the server 20 may have multiple canonical maps for various locations andmay determine that the second XR device 12.2 is in the same vicinity asthe vicinity of the first XR device 12.1 during the first session andsends the second XR device 12.2 the canonical map for that vicinity.

FIG. 44 shows the second XR device 12.2 beginning to identify PCFs forpurposes of generating Map 2. The second XR device 12.2 has onlyidentified a single PCF, namely PCF 1,2. The X, Y, and Z coordinates ofPCF 1,2 for the second XR device 12.2 may be (1,1,1). Map 2 has its ownorigin (Origin 2), which may be based on the head pose of device 2 atdevice start-up for the current head pose session. In some embodiments,the second XR device 12.2 may immediately attempt to localize Map 2 tothe canonical map. In some embodiments, Map 2 may not be able tolocalize into Canonical Map (Map 1) (e.g., localization may fail)because the system does not recognize any or enough overlap between thetwo maps. Localization may be performed by identifying a portion of thephysical world represented in a first map that is also represented in asecond map, and computing a transformation between the first map and thesecond map required to align those portions. In some embodiments, thesystem may localize based on PCF comparison between the local andcanonical maps. In some embodiments, the system may localize based onpersistent pose comparison between the local and canonical maps. In someembodiments, the system may localize based on key frame comparisonbetween the local and canonical maps.

FIG. 45 shows Map 2 after the second XR device 12.2 has identifiedfurther PCFs (PCF 1,2, PCF 3, PCF 4,5) of Map 2. The second XR device12.2 again attempts to localize Map 2 to the canonical map. Because Map2 has expanded to overlap with at least a portion of the Canonical Map,the localization attempt will succeed. In some embodiments, the overlapbetween the local tracking map, Map 2, and the Canonical Map may berepresented by PCFs, persistent poses, key frames, or any other suitableintermediate or derivative construct.

Furthermore, the second XR device 12.2 has associated Content123 andContent456 to PCFs 1,2 and PCF 3 of Map 2. Content123 has X, Y, and Zcoordinates relative to PCF 1,2 of (1,0,0). Similarly, the X, Y, and Zcoordinates of Content456 relative to PCF 3 in Map 2 are (1,0,0).

FIGS. 46A and 46B illustrate a successful localization of Map 2 to thecanonical map. Localization may be based on matching features in one mapto the other. With an appropriate transformation, here involving bothtranslation and rotation of one map with respect to the other, theoverlapping area/volume/section of the maps 1410 represent the commonparts to Map 1 and the canonical map. Since Map 2 created PCFs 3 and 4,5before localizing, and the Canonical map created PCFs a and c before Map2 was created, different PCFs were created to represent the same volumein real space (e.g., in different maps).

As shown in FIG. 47 , the second XR device 12.2 expands Map 2 to includePCFs a-d from the Canonical Map. The inclusion of PCFs a-d representsthe localization of Map 2 to the Canonical Map. In some embodiments, theXR system may perform an optimization step to remove duplicate PCFs fromoverlapping areas, such as the PCFs in 1410, PCF 3 and PCF 4,5. AfterMap 2 localizes, the placement of virtual content, such as Content456and Content123 will be relative to the closest updated PCFs in theupdated Map 2. The virtual content appears in the same real-worldlocation relative to the user, despite the changed PCF attachment forthe content, and despite the updated PCFs for Map 2.

As shown in FIG. 48 , the second XR device 12.2 continues to expand Map2 as further PCFs (e.g., PCFs e, f, g, and h) are identified by thesecond XR device 12.2, for example as the user walks around the realworld. It can also be noted that Map 1 has not expanded in FIGS. 47 and48 .

Referring to FIG. 49 , the second XR device 12.2 uploads Map 2 to theserver 20. The server 20 stores Map 2 together with the canonical map.In some embodiments, Map 2 may upload to the server 20 when the sessionends for the second XR device 12.2.

The canonical map within the server 20 now includes PCF i which is notincluded in Map 1 on the first XR device 12.1. The canonical map on theserver 20 may have expanded to include PCF i when a third XR device (notshown) uploaded a map to the server 20 and such a map included PCF i.

In FIG. 50 , the server 20 merges Map 2 with the canonical map to form anew canonical map. The server 20 determines that PCFs a to d are commonto the canonical map and Map 2. The server expands the canonical map toinclude PCFs e to h and PCF 1,2 from Map 2 to form a new canonical map.The canonical maps on the first and second XR devices 12.1 and 12.2 arebased on Map 1 and are outdated.

In FIG. 51 , the server 20 transmits the new canonical map to the firstand second XR devices 12.1 and 12.2. In some embodiments, this may occurwhen the first XR device 12.1 and second device 12.2 try to localizeduring a different or new or subsequent session. The first and second XRdevices 12.1 and 12.2 proceed as described above to localize theirrespective local maps (Map 1 and Map 2 respectively) to the newcanonical map.

As shown in FIG. 52 , the head coordinate frame 96 or “head pose” isrelated to the PCFs in Map 2. In some embodiments, the origin of themap, Origin 2, is based on the head pose of second XR device 12.2 at thestart of the session. As PCFs are created during the session, the PCFsare placed relative to the world coordinate frame, Origin 2. The PCFs ofMap 2 serve as a persistent coordinate frames relative to a canonicalcoordinate frame, where the world coordinate frame may be a previoussession's world coordinate frame (e.g., Map 1's Origin 1 in FIG. 40 ).These coordinate frames are related by the same transformation used tolocalize Map 2 to the canonical map, as discussed above in connectionwith FIG. 46B.

The transformation from the world coordinate frame to the headcoordinate frame 96 has been previously discussed with reference to FIG.9 . The head coordinate frame 96 shown in FIG. 52 only has twoorthogonal axes that are in a particular coordinate position relative tothe PCFs of Map 2, and at particular angles relative to Map 2. It shouldhowever be understood that the head coordinate frame 96 is in athree-dimensional location relative to the PCFs of Map 2 and has threeorthogonal axes within three-dimensional space.

In FIG. 53 , the head coordinate frame 96 has moved relative to the PCFsof Map 2. The head coordinate frame 96 has moved because the second user14.2 has moved their head. The user can move their head in six degreesof freedom (6dof). The head coordinate frame 96 can thus move in 6dof,namely in three-dimensions from its previous location in FIG. 52 andabout three orthogonal axes relative to the PCFs of Map 2. The headcoordinate frame 96 is adjusted when the real object detection camera 44and inertial measurement unit 48 in FIG. 9 respectively detect realobjects and motion of the head unit 22. More information regarding headpose tracking is disclosed in U.S. patent application Ser. No.16/221,065 entitled “Enhanced Pose Determination for Display Device” andis hereby incorporated by reference in its entirety.

FIG. 54 shows that sound may be associated with one or more PCFs. A usermay, for example, wear headphones or earphones with stereoscopic sound.The location of sound through headphones can be simulated usingconventional techniques. The location of sound may be located in astationary position so that, when the user rotates their head to theleft, the location of sound rotates to the right so that the userperceives the sound coming from the same location in the real world. Inthe present example, location of sound is represented by Sound123 andSound456. For purposes of discussion, FIG. 54 is similar to FIG. 48 inits analysis. When the first and second users 14.1 and 14.2 are locatedin the same room at the same or different times, they perceive Sound123and Sound456 coming from the same locations within the real world.

FIGS. 55 and 56 illustrate a further implementation of the technologydescribed above. The first user 14.1 has initiated a first session asdescribed with reference to FIG. 8 . As shown in FIG. 55 , the firstuser 14.1 has terminated the first session as indicated by the phantomlines. At the end of the first session, the first XR device 12.1uploaded Map 1 to the server 20. The first user 14.1 has now initiated asecond session at a later time than the first session. The first XRdevice 12.1 does not download Map 1 from the server 20 because Map 1 isalready stored on the first XR device 12.1. If Map 1 is lost, then thefirst XR device 12.1 downloads Map 1 from the server 20. The first XRdevice 12.1 then proceeds to build PCFs for Map 2, localizes to Map 1,and further develops a canonical map as described above. Map 2 of thefirst XR device 12.1 is then used for relating local content, a headcoordinate frame, local sound, etc. as described above.

Referring to FIGS. 57 and 58 , it may also be possible that more thanone user interacts with the server in the same session. In the presentexample, the first user 14.1 and the second user 14.2 are joined by athird user 14.3 with a third XR device 12.3. Each XR device 12.1, 12.2,and 12.3 begins to generate its own map, namely Map 1, Map 2, and Map 3,respectively. As the XR devices 12.1, 12.2, and 12.3 continue to developMaps 1, 2, and 3, the maps are incrementally uploaded to the server 20.The server 20 merges Maps 1, 2, and 3 to form a canonical map. Thecanonical map is then transmitted from the server 20 to each one of theXR devices 12.1, 12.2 and 12.3.

FIG. 59 illustrates aspects of a viewing method to recover and/or resethead pose, according to some embodiments. In the illustrated example, atAct 1400, the viewing device is powered on. At Act 1410, in response tobeing powered on, a new session is initiated. In some embodiments, a newsession may include establishing head pose. One or more capture deviceson a head-mounted frame secured to a head of a user capture surfaces ofan environment by first capturing images of the environment and thendetermining the surfaces from the images. In some embodiments, surfacedata may be combined with a data from a gravitational sensor toestablish head pose. Other suitable methods of establishing headpose maybe used.

At Act 1420, a processor of the viewing device enters a routine fortracking of head pose. The capture devices continue to capture surfacesof the environment as the user moves their head to determine anorientation of the head-mounted frame relative to the surfaces.

At Act 1430, the processor determines whether head pose has been lost.Head pose may become lost due to “edge” cases, such as too manyreflective surfaces, low light, blank walls, being outdoor, etc. thatmay result in low feature acquisition, or because of dynamic cases suchas a crowd that moves and forms part of the map. The routine at 1430allows for a certain amount of time, for example 10 seconds, to pass toallow enough time to determine whether head pose has been lost. If headpose has not been lost, then the processor returns to 1420 and againenters tracking of head pose.

If head pose has been lost at Act 1430, the processor enters a routineat 1440 to recover head pose. If head pose is lost due to low light,then a message such as the following example message or other similarmessage may be displayed to the user through a display of the viewingdevice:

THE SYSTEM IS DETECTING A LOW LIGHT CONDITION. PLEASE MOVE TO AN AREAWHERE THERE IS MORE LIGHT.

The system will continue to monitor whether there is sufficient lightavailable and whether head pose can be recovered. The system mayalternatively determine that low texture of surfaces is causing headpose to be lost, in which case the user is given the following prompt inthe display as a suggestion to improve capturing of surfaces:

THE SYSTEM CANNOT DETECT ENOUGH SURFACES WITH FINE TEXTURES. PLEASE MOVETO AN AREA WHERE THE SURFACES ARE LESS ROUGH IN TEXTURE AND MORE REFINEDIN TEXTURE.

At Act 1450, the processor enters a routine to determine whether headpose recovery has failed. If head pose recovery has not failed (i.e.,head pose recovery has succeeded), then the processor returns to Act1420 by again entering tracking of head pose. If head pose recovery hasfailed, the processor returns to Act 1410 to establish a new session. Aspart of the new session, all cached data is invalidated, whereafter headpose is established anew. Any suitable method of head tracking may beused in combination with the process described in FIG. 59 . U.S. patentapplication Ser. No. 16/221,065 describes head tracking and is herebyincorporated by reference in its entirety.

Remote Localization

Various embodiments may utilize remote resources to facilitatepersistent and consistent cross reality experiences between individualand/or groups of users. The inventors have recognized and appreciatedthat the benefits of operation of an XR device with canonical maps asdescribed herein can be achieved without downloading a set of canonicalmaps. FIG. 30 , discussed above, illustrates example implementationwhere canonical would be downloaded to device. The benefit of notdownloading maps, for example, may be achieved by sending feature andpose information to a remote service that maintains a set of canonicalmaps. According to one embodiment, a device seeking to use a canonicalmap to position virtual content in locations specified relative to thecanonical map may receive from the remote service one or moretransformations between the features and the canonical maps. Thosetransformations may be used on the device, which maintains informationabout the positions of those features in the physical world, to positionvirtual content in locations specified with respect to a canonical mapor to otherwise identify locations in the physical world that arespecified with respect to the canonical map.

In some embodiments, spatial information is captured by an XR device andcommunicated to a remote service, such as a cloud-based service, whichuses the spatial information to localize the XR device to a canonicalmap used by applications or other components of an XR system to specifythe location of virtual content with respect to the physical world. Oncelocalized, transforms that link a tracking map maintained by the deviceto the canonical map can be communicated to the device. The transformsmay be used, in conjunction with the tracking map, to determine aposition in which to render virtual content specified with respect tothe canonical map, or otherwise identify locations in the physical worldthat are specified with respect to the canonical map.

The inventors have realized that the data needed to be exchanged betweena device and a remote localization service can be quite small relativeto communicating map data, as might occur when a device communicates atracking map to a remote service and receives from that service a set ofcanonical maps for device-based localization. In some embodiments,performing localization functions on cloud resources requires only asmall amount of information to be transmitted from the device to theremote service. It is not a requirement, for example, that a fulltracking map be communicated to the remote service to performlocalization. In some embodiments, features and pose information, suchas might be stored in connection with a persistent pose, as describedabove, might be transmitted to the remote server. In embodiments inwhich features are represented by descriptors, as described above, theinformation uploaded may be even smaller.

The results returned to the device from the localization service may beone or more transformations that relate the uploaded features toportions of a matching canonical map. Those transformations may be usedwithin the XR system, in conjunction with its tracking map, foridentifying locations of virtual content or otherwise identifyinglocations in the physical world. In embodiments in which persistentspatial information, such as PCF's as described above, are used tospecify locations with respect to a canonical map, the localizationservice may download to the device transformations between the featuresand one or more PCF's after a successful localization.

As a result, network bandwidth consumed by communications between an XRdevice and a remote service for performing localization may be low. Thesystem may therefore support frequent localization, enabling each deviceinteracting with the system to quickly obtain information forpositioning virtual content or performing other location-basedfunctions. As a device moves within the physical environment, it mayrepeat requests for updated localization information. Additionally, adevice may frequently obtain updates to the localization information,such as when the canonical maps change, such as through merging ofadditional tracking maps to expand the map or increase their accuracy.

Further, uploading features and downloading transformations can enhanceprivacy in an XR system that shares map information among multiple usersby increasing the difficulty of obtaining maps by spoofing. Anunauthorized user, for example, may be thwarted from obtaining a mapfrom the system by sending a fake request for a canonical maprepresenting a portion of the physical world in which that unauthorizeduser is not located. An unauthorized user would be unlikely to haveaccess to the features in the region of the physical world for which itis requesting map information if not physically present in that region.In embodiments in which feature information is formatted as featuredescriptions, the difficulty in spoofing feature information in arequest for map information would be compounded. Further, when thesystem returns a transformation intended to be applied to a tracking mapof a device operating in the region about which location information isrequested, the information returned by the system is likely to be oflittle or no use to an imposter.

According to one embodiment, a localization service is implemented as acloud based micro-service. In some examples, implementing a cloud-basedlocalization service can help save device compute resources and mayenable computations required for localization to be performed with verylow latency. Those operations can be supported by nearly infinitecompute power or other computing resources available by provisioningadditional cloud resources, ensuring scalability of the XR system tosupport numerous devices. In one example, many canonical maps can bemaintained in memory for nearly instant access, or alternatively storedin high availability devices reducing system latency.

Further, performing localization for multiple devices in a cloud servicemay enable refinements to the process. Localization telemetry andstatistics can provide information on which canonical maps to have inactive memory and/or high availability storage. Statistics for multipledevices may be used, for example, to identify most frequently accessedcanonical maps.

Additional accuracy may also be achieved as a result of processing in acloud environment or other remote environment with substantialprocessing resources relative to a remote device. For example,localization can be made on higher density canonical maps in the cloudrelative to processing performed on local devices. Maps may be stored inthe cloud, for example, with more PCF's or a greater density of featuredescriptors per PCF, increasing the accuracy of a match between a set offeatures from a device and a canonical map.

FIG. 61 is a schematic diagram of an XR system 6100. The user devicesthat display cross reality content during user sessions can come in avariety of forms. For example, a user device can be a wearable XR device(e.g., 6102) or a handheld mobile device (e.g., 6104). As discussedabove, these devices can be configured with software, such asapplications or other components, and/or hardwired to generate localposition information (e.g., a tracking map) that can be used to rendervirtual content on their respective displays.

Virtual content positioning information may be specified with respect toglobal location information, which may be formatted as a canonical mapcontaining one or more PCF's, for example. According to someembodiments, the system 6100 is configured with cloud-based servicesthat support the functioning and display of the virtual content on theuser device.

In one example, localization functions are provided as a cloud-basedservice 6106, which may be a micro-service. Cloud-based service 6106 maybe implemented on any of multiple computing devices, from whichcomputing resources may be allocated to one or more services executingin the cloud. Those computing devices may be interconnected with eachother and accessibly to devices, such as a wearable XR device 6102 andhand-held device 6104. Such connections may be provided over one or morenetworks.

In some embodiments, the cloud-based service 6106 is configured toaccept descriptor information from respective user devices and“localize” the device to a matching canonical map or maps. For example,the cloud-based localization service matches descriptor informationreceived to descriptor information for respective canonical map(s). Thecanonical maps may be created using techniques as described above thatcreate canonical maps by merging maps provided by one or more devicesthat have image sensors or other sensors that acquire information abouta physical world. However, it may not be a requirement that thecanonical maps be created by the devices that access them, as such mapsmay be created by a map developer, for example, who may publish the mapsby making them available to localization service 6106.

According to some embodiments, the cloud service handles canonical mapidentification, and may include operations to filter a repository ofcanonical maps to a set of potential matches. Filtering may be performedas illustrated in FIG. 29 , or by using any subset of the filtercriteria and other filter criteria instead of or in addition to thefilter criteria shown in FIG. 29 . In one embodiment, geographic datacan be used to limit a search for matching canonical map to mapsrepresenting areas proximate to the device requesting localization. Forexample, area attributes such as Wi-Fi signal data, Wi-Fi fingerprintinformation, GPS data, and/or other device location information can beused as a coarse filter on stored canonical maps, and thereby limitanalysis of descriptors to canonical maps known or likely to be inproximity to the user device. Similarly, location history of each devicemay be maintained by the cloud service such that canonical maps in thevicinity of the device's last location are preferentially searched. Insome examples, filtering can include the functions discussed above withrespect to FIGS. 31B, 32, 33, and 34 .

FIG. 62 is an example process flow that can be executed by devices touse a cloud-based service to localize the device's position withcanonical map(s) and receive transform information specifying one ormore transformations between the device local coordinate system and thecoordinate system of a canonical map. Various embodiments and examplesdescribe the transform as specifying a transformation from a firstcoordinate frame to a second. Other embodiments include transforms fromthe second to the first coordinate frame. Any in yet other embodiments,the transform enables transition from one coordinate frame to another,the resulting coordinate frames depend only on the desired coordinateframe output (including, for example, the coordinate frame in which todisplay content). In yet further embodiments, the coordinate systemtransform enables determination of a first coordinate frame from thesecond and the second coordinate from the first.

According to some embodiments, information reflecting a transform foreach persistent pose defined with respect to the canonical map can becommunicated to device.

According to one embodiment, process 6200 can begin at 6202 with a newsession. Starting a new session on the device may initiate capture ofimage information to build a tracking map for the device. Additionally,the device may send a message, registering with a server of alocalization service, prompting the server to create a session for thatdevice.

In some embodiments, starting a new session on a device optionally mayinclude sending adjustment data from the device to the localizationservice. The localization service returns to the device one or moretransforms computed based on the set of features and associated poses.If the poses of the features are adjusted based on device-specificinformation before computation of the transformation and/or thetransformations are adjusted based on device-specific information aftercomputation of the transformation, rather than perform thosecomputations on the device, the device specific information might besent to the localization service, such that the localization service mayapply the adjustments. As a specific example, sending device-specificadjustment information may include capturing calibration data forsensors and/or displays. The calibration data may be used, for example,to adjust the locations of feature points relative to a measuredlocation. Alternatively, or additionally, the calibration data may beused to adjust the locations at which the display is commanded to rendervirtual content so as to appear accurately positioned for thatparticular device. This calibration data may be derived, for example,from multiple images of the same scene taken with sensors on the device.The locations of features detected in those images may be expressed as afunction of sensor location, such that multiple images yield a set ofequations that may be solved for the sensor location. The computedsensor location may be compared to a nominal position, and thecalibration data may be derived from any differences. In someembodiments, intrinsic information about the construction of the devicemay also enable calibration data to be computed for the display, in someembodiments.

In embodiments in which calibration data is generated for the sensorsand/or display, the calibration data may be applied at any point in themeasurement or display process. In some embodiments, the calibrationdata may be sent to the localization server, which may store thecalibration data in a data structure established for each device thathas registered with the localization server and is therefore in asession with the server. The localization server may apply thecalibration data to any transformations computed as part of alocalization process for the device supplying that calibration data. Thecomputational burden of using the calibration data for greater accuracyof sensed and/or displayed information is thus borne by the calibrationservice, providing a further mechanism to reduce processing burden onthe devices.

Once the new session is established, process 6200 may continue at 6204with capture of new frames of the device's environment. Each frame canbe processed to generate descriptors (including for example, DSF valuesdiscussed above) for the captured frame at 6206. These values may becomputed using some or all of the techniques described above, includingtechniques as discussed above with respect to FIGS. 14,22, and 23 . Asdiscussed, the descriptors may be computed as a mapping of the featurepoints or, in some embodiments a mapping of a patch of an image around afeature point, to a descriptor. The descriptor may have a value thatenables efficient matching between newly acquired frames/images andstored maps. Moreover, the number of features extracted from an imagemay be limited to a maximum number of features points per image, such as200 feature points per image. The feature points may be selected torepresent interest points, as described above. Accordingly, acts 6204and 6206 may be performed as part of a device process of forming atracking map or otherwise periodically collecting images of the physicalworld around the device, or may be, but need not be, separatelyperformed for localization.

Feature extraction at 6206 may include appending pose information to theextracted features at 6206. The pose information may be a pose in thedevice's local coordinate system. In some embodiments, the pose may berelative to a reference point in the tracking map, such as a persistentpose, as discussed above. Alternatively, or additionally, the pose maybe relative to the origin of a tracking map of the device. Such anembodiment may enable the localization service as described herein toprovide localization services for a wide range of devices, even if theydo not utilize persistent poses. Regardless, pose information may beappended to each feature or each set of features, such that thelocalization service may use the pose information for computing atransformation that can be returned to the device upon matching thefeatures to features in a stored map.

The process 6200 may continue to decision block 6207 where a decision ismade whether to request a localization. One or more criteria may beapplied to determine whether to request a localization. The criteria mayinclude passage of time, such that a device may request localizationafter some threshold amount of time. For example, if a localization hasnot been attempted within a threshold amount of time, the process maycontinue from decision block 6207 to act 6208 where localization isrequested from the cloud. That threshold amount of time may be between10 and 30 seconds, such as 25 seconds, for example. Alternatively, oradditionally, localization may be triggered by motion of a device. Adevice executing the process 6200 may track its motion using an IMU andits tracking map, and initiate localization upon detection of motionexceeding a threshold distance from the location where the device lastrequested localization. The threshold distance may be between 1 and 10meters, such as between 3 and 5 meters, for example. As yet a furtheralternative, localization may be triggered in response to an event, suchas when a device creates a new persistent pose or the current persistentpose for the device changes, as described above.

In some embodiments, decision block 6207 may be implemented such thatthe thresholds for triggering localization may be establisheddynamically. For example, in environments in which features are largelyuniform such that there may be a low confidence in matching a set ofextracted features to features of a stored map, localization may berequested more frequently to increase the chances that at least oneattempt at localization will succeed. In such a scenario, the thresholdsapplied at decision block 6207 may be decreased. Similarly, in anenvironment in which there are relatively few features, the thresholdsapplied at decision block 6207 may be decreased so as to increase thefrequency of localization attempts.

Regardless of how the localization is triggered, when triggered, theprocess 6200 may proceed to act 6208 where the device sends a request tothe localization service, including data used by the localizationservice to perform localization. In some embodiments, data from multipleimage frames may be provided for a localization attempt. Thelocalization service, for example, may not deem localization successfulunless features in multiple image frames yield consistent localizationresults. In some embodiments, process 6200 may include saving featuredescriptors and appended pose information into a buffer. The buffer may,for example, be a circular buffer, storing sets of features extractedfrom the most recently captured frames. Accordingly, the localizationrequest may be sent with a number of sets of features accumulated in thebuffer. In some settings, a buffer size is implemented to accumulate anumber of sets of data that will be more likely to yield successfullocalization. In some embodiments, a buffer size may be set toaccumulate features from two, three, four, five, six, seven, eight,nine, or ten frames, for example). Optionally, the buffer size can havea baseline setting which can be increased responsive to localizationfailures. In some examples, increasing the buffer size and correspondingnumber of sets of features transmitted reduces the likelihood thatsubsequent localization functions fail to return a result.

Regardless of how the buffer size is set, the device may transfer thecontents of the buffer to the localization service as part of alocalization request. Other information may be transmitted inconjunction with the feature points and appended pose information. Forexample, in some embodiments, geographic information may be transmitted.The geographic information may include, for example, GPS coordinates ora wireless signature associated with the devices tracking map or currentpersistent pose.

In response to the request sent at 6208, a cloud localization servicemay analyze the feature descriptors to localize the device into acanonical map or other persistent map maintained by the service. Forexample, the descriptors are matched to a set of features in a map towhich the device is localized. The cloud-based localization service mayperform localization as described above with respect to device-basedlocalization (e.g., can rely on any of the functions discussed above forlocalization (including, map ranking, map filtering, locationestimation, filtered map selection, examples in FIGS. 44-46 , and/ordiscussed with respect to a localization module, PCF and/or PPidentification and matching etc.). However, instead of communicatingidentified canonical maps to a device (e.g., in device localization),the cloud-based localization service may proceed to generate transformsbased on the relative orientation of feature sets sent from the deviceand the matching features of the canonical maps. The localizationservice may return these transforms to the device, which may be receivedat block 6210.

In some embodiments, the canonical maps maintained by the localizationservice may employ PCF's, as described above. In such an embodiment, thefeature points of the canonical maps that match the feature points sentfrom the device may have positions specified with respect to one or morePCF's. Accordingly, the localization service may identify one or morecanonical maps and may compute a transformation between the coordinateframe represented in the poses sent with the request for localizationand the one or more PCF's. In some embodiments, identification of theone or more canonical maps is assisted by filtering potential maps basedon geographic data for a respective device. For example, once filteredto a candidate set (e.g., by GPS coordinate, among other options) thecandidate set of canonical maps can be analyzed in detail to determinematching feature points or PCFs as described above.

The data returned to the requesting device at act 6210 may be formattedas a table of persistent pose transforms. The table can be accompaniedby one or more canonical map identifiers, indicating the canonical mapsto which the device was localized by the localization service. However,it should be appreciated that the localization information may beformatted in other ways, including as a list of transforms, withassociated PCF and/or canonical map identifiers.

Regardless of how the transforms are formatted, at act 6212 the devicemay use these transforms to compute the location at which to rendervirtual content for which a location has been specified by anapplication or other component of the XR system relative to any of thePCF's. This information may alternatively or additionally be used on thedevice to perform any location-based operation in which a location isspecified based on the PCF's.

In some scenarios, the localization service may be unable to matchfeatures sent from a device to any stored canonical map or may not beable to match a sufficient number of the sets of features communicatedwith the request for the localization service to deem a successfullocalization occurred. In such a scenario, rather than returningtransformations to the device as described above in connection with act6210, the localization service may indicate to the device thatlocalization failed. In such a scenario, the process 6200 may branch atdecision block 6209 to act 6230, where the device may take one or moreactions for failure processing. These actions may include increasing thesize of the buffer holding feature sets sent for localization. Forexample, if the localization service does not deem a successfullocalization unless three sets of features match, the buffer size may beincreased from five to six, increasing the chances that three of thetransmitted sets of features can be matched to a canonical mapmaintained by the localization service.

Alternatively, or additionally, failure processing may include adjustingan operating parameter of the device to trigger more frequentlocalization attempts. The threshold time between localization attemptsand/or the threshold distance may be decreased, for example. As anotherexample, the number of feature points in each set of features may beincreased. A match between a set of features and features stored withina canonical map may be deemed to occur when a sufficient number offeatures in the set sent from the device match features of the map.Increasing the number of features sent may increase the chances of amatch. As a specific example, the initial feature set size may be 50,which may be increased to 100, 150, and then 200, on each successivelocalization failure. Upon successful match, the set size may then bereturned to its initial value.

Failure processing may also include obtaining localization informationother than from the localization service. According to some embodiments,the user device can be configured to cache canonical maps. Cached mapspermit devices to access and display content where the cloud isunavailable. For example, cached canonical maps permit device-basedlocalization in the event of communication failure or otherunavailability.

According to various embodiments, FIG. 62 describes a high-level flowfor a device initiating cloud-based localization. In other embodiments,various ones or more of the illustrated steps can be combined, omitted,or invoke other processes to accomplish localization and ultimatelyvisualization of virtual content in a view of a respective device.

Further, it should be appreciated that, though the process 6200 showsthe device determining whether to initiate localization at decisionblock 6207, the trigger for initiating localization may come fromoutside the device, including from the localization service. Thelocalization service, for example, may maintain information about eachof the devices that is in a session with it. That information, forexample, may include an identifier of a canonical map to which eachdevice most recently localized. The localization service, or othercomponents of the XR system, may update canonical maps, including usingtechniques as described above in connection with FIG. 26 . When acanonical map is updated, the localization service may send anotification to each device that most recently localized to that map.That notification may serve as a trigger for the device to requestlocalization and/or may include updated transformations, recomputedusing the most recently sent sets of features from the device.

FIGS. 63A, B, and C are an example process flow showing operations andcommunication between a device and cloud services. Shown at blocks 6350,6352, 6354, and 6456 are example architecture and separation betweencomponents participating in the cloud-based localization process. Forexample, the modules, components, and/or software that are configured tohandle perception on the user device are shown at 6350 (e.g., 660, FIG.6A). Device functionality for persisted world operations is shown at6352 (including, for example, as described above and with respect topersisted world module (e.g., 662, FIG. 6A)). In other embodiments, theseparation between 6350 and 6352 is not needed and the communicationshown can be between processes executing on the device.

Similarly, shown at block 6354 is a cloud process configured to handlefunctionality associated with passable world/passable world modeling(e.g., 802, 812, FIG. 26 ). Shown at block 6356 is a cloud processconfigured to handle functionality associated with localizing a device,based on information sent from a device, to one or more maps of arepository of stored canonical maps.

In the illustrated embodiment, process 6300 begins at 6302 when a newsession starts. At 6304 sensor calibration data is obtained. Thecalibration data obtained can be dependent on the device represented at6350 (e.g., number of cameras, sensors, positioning devices, etc.). Oncethe sensor calibration is obtained for the device, the calibrations canbe cached at 6306. If device operation resulted in a change in frequencyparameters (e.g., collection frequency, sampling frequency, matchingfrequency, among other options) the frequency parameters are reset tobaseline at 6308.

Once the new session functions are complete (e.g., calibration, steps6302-6306) process 6300 can continue with capture of a new frame 6312.Features and their corresponding descriptors are extracted from theframe at 6314. In some examples, descriptors can comprise DSF's, asdiscussed above. According to some embodiments, the descriptors can havespatial information attached to them to facilitate subsequent processing(e.g., transform generation). Pose information (e.g., information,specified relative to the device's tracking map for locating thefeatures in the physical world as discussed above) generated on thedevice can be appended to the extracted descriptors at 6316.

At 6318, the descriptor and pose information is added to a buffer. Newframe capture and addition to the buffer shown in steps 6312-6318 isexecuted in a loop until a buffer size threshold is exceeded at 6319.Responsive to a determination that the buffer size has been met, alocalization request is communicated from the device to the cloud at6320. According to some embodiments, the request can be handled by apassable world service instantiated in the cloud (e.g., 6354). Infurther embodiments, functional operations for identifying candidatecanonical maps can be segregated from operations for actual matching(e.g., shown as blocks 6354 and 6356). In one embodiment, a cloudservice for map filtering and/or map ranking can be executed at 6354 andprocess the received localization request from 6320. According to oneembodiment, the map ranking operations are configured to determine a setof candidate maps at 6322 that are likely to include a device'slocation.

In one example, the map ranking function includes operations to identifycandidate canonical maps based on geographic attributes or otherlocation data (e.g., observed or inferred location information). Forexample, other location data can include Wi-Fi signatures or GPSinformation.

According to other embodiments, location data can be captured during across reality session with the device and user. Process 6300 can includeadditional operations to populate a location for a given device and/orsession (not shown). For example, the location data may be stored asdevice area attribute values and the attribute values used to selectcandidate canonical maps proximate to the device's location.

Any one or more of the location options can be used to filter sets ofcanonical maps to those likely to represent an area including thelocation of a user device. In some embodiments, the canonical maps maycover relatively large regions of the physical world. The canonical mapsmay be segmented into areas such that selection of a map may entailselection of a map area. A map area, for example may be on the order oftens of meters squared. Thus, the filtered set of canonical maps may bea set of areas of the maps.

According to some embodiments, a localization snapshot can be built fromthe candidate canonical maps, posed features, and sensor calibrationdata. For example, an array of candidate canonical maps, posed features,and sensor calibration information can be sent with a request todetermine specific matching canonical maps. Matching to a canonical mapcan be executed based on descriptors received from a device and storedPCF data associated with the canonical maps.

In some embodiments, a set of features from the device is compared tosets of features stored as part of the canonical map. The comparison maybe based on the feature descriptors and/or pose. For example, acandidate set of features of a canonical map may be selected based onthe number of features in the candidate set that have descriptorssimilar enough to the descriptors of the feature set from the devicethat they could be the same feature. The candidate set, for example, maybe features derived from an image frame used in forming the canonicalmap.

In some embodiments, if the number of similar features exceeds athreshold, further processing may be performed on the candidate set offeatures. Further processing may determine the degree to which the setof posed features from the device can be aligned with the features ofthe candidate set. The set of features from the canonical map, like thefeatures from the device, may be posed.

In some embodiments, features are formatted as a highly dimensionalembedding (e.g., DSF, etc.) and may be compared using a nearest neighborsearch. In one example, the system is configured (e.g., by executingprocess 6200 and/or 6300) to find the top two nearest neighbors usingEuclidian distance, and may execute a ratio test. If the closestneighbor is much closer than the second closest neighbor, the systemconsiders the closest neighbor to be a match. “Much closer” in thiscontext may be determined, for example, by the ratio of Euclideandistance relative to the second nearest neighbor is more than athreshold times the Euclidean distance relative to the nearest neighbor.Once a feature from the device is considered to be a “match” to afeature in canonical map, the system may be configured to use the poseof the matching features to compute a relative transformation. Thetransformation developed from the pose information may be used toindicate the transformation required to localize the device to thecanonical map.

The number of inliers may serve as an indication of the quality of thematch. For example, in the case of DSF matching, the number of inliersreflects the number of features that were matched between receiveddescriptor information and stored/canonical maps. In furtherembodiments, inliers may be determined in this embodiment by countingthe number of features in each set that “match”.

An indication of the quality of a match may alternatively oradditionally be determined in other ways. In some embodiments, forexample, when a transformation is computed to localize a map from adevice, which may contain multiple features, to a canonical map, basedon relative pose of matching features, statistics of the transformationcomputed for each of multiple matching features may serve as qualityindication. A large variance, for example, may indicate a poor qualityof match. Alternatively, or additionally, the system may compute, for adetermined transformation, a mean error between features with matchingdescriptors. The mean error may be computed for the transformation,reflecting the degree of positional mismatch. A mean squared error is aspecific example of an error metric. Regardless of the specific errormetric, if the error is below a threshold, the transformation may bedetermined to be usable for the features received from the device, andthe computed transformation is used for localizing the device.Alternatively, or additionally, the number of inliers may also be usedin determining whether there is a map that matches a device's positionalinformation and/or descriptors received from a device.

As noted above, in some embodiments, a device may send multiple sets offeatures for localization. Localization may be deemed successful when atleast a threshold number of sets of features match, with an error belowa threshold and a number of inliers above a threshold, a set of featuresfrom the canonical map. That threshold number, for example, may be threesets of features. However, it should be appreciated that the thresholdused for determining whether a sufficient number of sets of featureshave suitable values may be determined empirically or in other suitableways. Likewise, other thresholds or parameters of the matching process,such as degree of similarity between feature descriptors to be deemedmatching, the number of inliers for selection of a candidate set offeatures, and/or the magnitude of the mismatch error, may similarly bedetermined empirically or in other suitable ways.

Once a match is determined, a set of persistent map features associatedwith the matched canonical map or maps is identified. In embodiments inwhich the matching is based on areas of maps, the persistent mapfeatures may be the map features in the matching areas. The persistentmap features may be persistent poses or PCF's as described above. In theexample of FIG. 63 , the persistent map features are persistent poses.

Regardless of the format of the persistent map features, each persistentmap feature may have a predetermined orientation relative to thecanonical map in which it is a part. This relative orientation may beapplied to the transformation computed to align the set of features fromthe device with the set of features from the canonical map to determinea transformation between the set of features from the device and thepersistent map feature. Any adjustments, such as might be derived fromcalibration data, may then be applied to this computed transformation.The resulting transformation may be the transformation between the localcoordinate frame of the device and the persistent map feature. Thiscomputation may be performed for each persistent map feature of amatching map area, and the results may be stored in a table, denoted asthe persistent_pose_table in 6326.

In one example, block 6326 returns a table of persistent posetransforms, canonical map identifiers, and number of inliers. Accordingto some embodiments, the canonical map ID is an identifier for uniquelyidentifying a canonical map and a version of the canonical map (or areaof a map, in embodiments in which localization is based on map areas).

In various embodiments, the computed localization data can be used topopulate localization statistics and telemetry maintained by thelocalization service at 6328. This information may be stored for eachdevice, and may be updated for each localization attempt, and may becleared when the device's session ends. For example, which maps werematched by a device can be used to refine map ranking operations. Forexample, maps covering the same area to which the device previouslymatched may be prioritized in the ranking. Likewise, maps coveringadjacent areas may be give higher priority over more remote areas.Further, the adjacent maps might be prioritized based on a detectedtrajectory of the device over time, with map areas in the direction ofmotion being given higher priority over other map areas. Thelocalization service may use this information, for example, upon asubsequent localization request from the device to limit the maps or mapareas searched for candidate sets of features in the stored canonicalmaps. If a match, with low error metrics and/or a large number orpercentage of inliers, is identified in this limited area, processing ofmaps outside the area may be avoided.

Process 6300 can continue with communication of information from thecloud (e.g., 6354) to the user device (e.g., 6352). According to oneembodiment, a persistent pose table and canonical map identifiers arecommunicated to the user device at 6330. In one example, the persistentpose table can be constructed of elements including at least a stringidentifying a persistent pose ID and a transform linking the device'stracking map and the persistent pose. In embodiments in which thepersistent map features are PCF's, the table may, instead, indicatetransformations to the PCF's of the matching maps.

If localization fails at 6336, process 6300 continues by adjustingparameters that may increase the amount of data sent from a device tothe localization service to increases the chances that localization willsucceed. Failure, for example, may be indicated when no sets of featuresin the canonical map can be found with more than a threshold number ofsimilar descriptors or when the error metric associated with alltransformed sets of candidate features is above a threshold. As anexample of a parameter that may be adjusted, the size constraint for thedescriptor buffer may be increased (of 6319). For example, where thedescriptor buffer size is five, localization failure can trigger anincrease to at least six sets of features, extracted from at least siximage frames. In some embodiments, process 6300 can include a descriptorbuffer increment value. In one example, the increment value can be usedto control the rate of increase in the buffer size, for example,responsive to localization failures. Other parameters, such asparameters controlling the rate of localization requests, may be changedupon a failure to find matching canonical maps.

In some embodiments, execution of 6300 can generate an error conditionat 6340, which includes execution where the localization request failsto work, rather than return a no match result. An error, for example,may occur as a result of a network error making the storage holding adatabase of canonical maps unavailable to a server executing thelocalization service or a received request for localization servicescontaining incorrectly formatted information. In the event of an errorcondition, in this example, the process 6300 schedules a retry of therequest at 6342.

When a localization request is successful, any parameters adjusted inresponse to a failure may be reset. At 6332, process 6300 can continuewith an operation to reset frequency parameters to any default orbaseline. In some embodiments, 6332 is executed regardless of anychanges thus ensuring baseline frequency is always established.

The received information can be used by the device at 6334 to update acache localization snapshot. According to various embodiments, therespective transforms, canonical maps identifiers, and otherlocalization data can be stored by the device and used to relatelocations specified with respect to the canonical maps, or persistentmap features of them such as persistent poses or PCF's to locationsdetermined by the device with respect to its local coordinate frame,such as might be determined from its tracking map.

Various embodiments of processes for localization in the cloud canimplement any one or more of the preceding steps and be based on thepreceding architecture. Other embodiments may combine various ones ormore of the preceding steps, execute steps simultaneously, in parallel,or in another order.

According to some embodiments, localization services in the cloud in thecontext of cross reality experiences can include additionalfunctionality. For example, canonical map caching may be executed toresolve issues with connectivity. In some embodiments, the device mayperiodically download and cache canonical maps to which it haslocalized. If the localization services in the cloud are unavailable,the device may run localizations itself (e.g., as discussedabove—including with respect to FIG. 26 ). In other embodiments, thetransformations returned from localization requests can be chainedtogether and applied in subsequent sessions. For example, a device maycache a train of transformations and use the sequence of transformationsto establish localization.

Various embodiments of the system can use the results of localizationoperations to update transformation information. For example, thelocalization service and/or a device can be configured to maintain stateinformation on a tracking map to canonical map transformations. Thereceived transformations can be averaged over time. According to oneembodiment, the averaging operations can be limited to occur after athreshold number of localizations are successful (e.g., three, four,five, or more times). In further embodiments, other state informationcan be tracked in the cloud, for example, by a passable world module. Inone example, state information can include a device identifier, trackingmap ID, canonical map reference (e.g., version and ID), and thecanonical map to tracking map transform. In some examples, the stateinformation can be used by the system to continuously update and getmore accurate canonical map to tracking map transforms with everyexecution of the cloud-based localization functions.

Additional enhancements to cloud-based localization can includecommunicating to devices outliers in the sets of features that did notmatch features in the canonical maps. The device may use thisinformation, for example, to improve its tracking map, such as byremoving the outliers from the sets of features used to build itstracking map. Alternatively, or additionally, the information from thelocalization service may enable the device to limit bundle adjustmentsfor its tracking map to computing adjustments based on inlier featuresor to otherwise impose constraints on the bundle adjustment process.

According to another embodiment, various sub-processes or additionaloperations can be used in conjunction and/or as alternatives to theprocesses and/or steps discussed for cloud-based localization. Forexample, candidate map identification may include accessing canonicalmaps based on area identifiers and/or area attributes stored withrespective maps.

Wireless Fingerprint Assisted Localization

Regardless of whether localization is performed in a localizationservice (e.g., which may store sets of canonical maps), or on a device(e.g., which may receive a set of canonical maps for localization), thelocalization process may be more efficient by efficiently filtering auniverse of canonical maps against which localization may be attempted.In some embodiments, location metadata, such as wireless fingerprints,descriptive of relatively small regions of the physical world may beassociated with information about the physical world acquired by aportable device and may be stored in connection with canonical mapsagainst which localization may be attempted. Selecting maps, or portionsof maps, based on similarity of wireless fingerprint to the informationcaptured by the portable device may simplify the localization process.

A wireless fingerprint may be constructed from characteristics ofwireless signals received in a relatively small region of the physicalworld. In the exemplary embodiment described herein, Wi-Fi signals areused as an example of wireless signals. Specifically, BSSID and RSSI areexamples of characteristics of wireless signals received. Though, inother embodiments, other characteristics of signals from wirelessnetwork access points, or other wireless communications, alternativelyor additionally may be used to form a signature. In some embodiments,GPS and/or Bluetooth beacons may be used to form a wireless fingerprint,alone or in combination with Wi-Fi signals.

Further, in some exemplary embodiments described herein, wirelessfingerprints are associated with persistent poses, which are an exampleof persistent information about the physical world captured by aportable device. Persistent poses are recognized by processing imageinformation captured on the portable device to detect a cluster offeatures indicative of what is likely to be persistent content in thephysical world. The persistent pose is then integrated into a trackingmap. The persistent poses are distributed throughout the tracking map,spaced by distances corresponding to 2 to 4 meters in the physicalworld, for example. The tracking map may be segmented into tiles, witheach tile encompassing a persistent pose.

Persistent coordinate frames (PCFs) in canonical maps are an example ofpersistent information against which a device may localize. The PCFs mayhave wireless signatures attached to them. As described above, canonicalmaps may be formed from tracking maps, such as using a map merge processas described above. In promoting or merging tracking maps into canonicalmaps, PCFs may be created from one or more persistent poses of thetracking maps.

FIGS. 64 through 68 illustrate an example of a portable devicegenerating a tracking map containing Wi-Fi fingerprints for use in Wi-Fiassisted localization or other functions, according to some embodiments.

In FIG. 64 , a user 6402 with a portable device is shown in athree-dimensional (3D) environment containing wireless network accesspoints 6404 a through 6404 e. In some embodiments, the portable deviceof user 6402 may receive signals from nearby network access points, forexample network access point 6404 a, 6404 b, and 6404 c as indicated inFIG. 64 . Wireless hardware on the portable device may determine anetwork access point identifier and signal strength indicator value foreach network access point for which a signal is detected. Wirelesschipsets, for example, may be configured to perform a scan for availablewireless network. That scan function may be initiated to obtain wirelessinformation as described herein.

In some embodiments, the network access point identifier may be a basicservice set identifier (BSSID) and the signal strength indicator valuemay be a received signal strength indicator (RSSI) value. In someembodiments, other information about the network access points may becollected in addition to or instead of network access point identifiersand signal strength indicators. In some embodiments, the network accesspoint information may be used to form a Wi-Fi fingerprint.

The network access point information 6406 may be stored in associationwith persistent location information 6408 in a tile 6410 of a map 6412.For example, the persistent poses may be stored as data structures innon-volatile memory within or connected over a network to the portabledevice. The wireless information may be stored as a list of BSSID, RSSItuples in this data structure, for example. In some embodiments, thepersistent location information 6408 may comprise a persistentcoordinate frame or persistent pose, as described above. In the exampleof FIG. 64 , persistent location information 6408 is a persistent pose,and is selected as the closest persistent pose to user 6402, at the timethe wireless signals are captured. In this context, the closestpersistent pose is the pose determined based on the distance between theuser and the location in the 3D environment of features associated withthe persistent pose, although other methods may be used.

In some embodiments, the persistent location information 6408 mayinclude other information about the location, position, or orientationof the portable device in the 3D environment. In some embodiments,multiple pieces of location information and associated network accesspoint information may be stored within a single tile. The wirelessinformation, for example, may be captured as the portable device isbuilding a tracking map, such that wireless information may be capturedand stored as new persistent poses are created.

FIG. 65 illustrates user 6402 moving within the 3D environment. In theillustrated example, the portable device of user 6402 receives signalsfrom the same wireless network access points 6404 a, 6404 b, and 6404 c,but obtains new signal strength values associated with these wirelessnetwork access points because of the change in proximity between theportable device and the wireless network access points 6404 a-6404 e. Inthis example, location of the user has caused the user to enter a spacethat is not yet mapped in the tracking map such that a new persistentpose is created. In some embodiments, the new persistent pose may definea new tile for the tracking map. In some embodiments, a grid of tilesmay be predefined (e.g., fixed size and shape relative to other tiles)but may not contain data (e.g., if the area has not been mappedpreviously until the user enters that tile, and in some embodiments, apersistent pose and/or PCF is created. The new network access pointinformation 6506 may be stored with the new persistent locationinformation 6508 in a new tile 6510 of map 6412 as illustrated. In someembodiments the new tile 6510 may be created, for example, because thedistance the portable device has moved since a prior tile was createdexceeds a threshold.

FIG. 66 illustrates user 6402 moving further within the 3D environment.In this example, the portable device of user 6402 receives signals fromwireless network access points 6404 a, 6404 b, 6404 c, and 6404 d. Asdiscussed in connection with FIGS. 64 and 65 , the network access pointinformation 6606 and persistent location information 6608 may be storedin a tile 6610 of the map 6412.

The wireless information associated with the persistent pose, as isillustrated in FIGS. 64, 65 and 66 may be the initial wireless signaturefor that tile. In some embodiments, the wireless signature for a tilemay be refined as a user device continues to operate and collect morewireless information.

In FIG. 67 , user 6402 is shown at the same location within the 3Denvironment 6102 as in FIG. 66 . In some embodiments, this may occurwhen the user remains in the same location for a duration of time. Atile, for example, may correspond to an area between 2 and 4 squaremeters and a wireless scan may be performed approximately every 20 to 60seconds. As a result, a user often may not move far enough to move fromone tile to another in the time between scans. Alternatively, oradditionally, this may occur when the user returns to the same locationafter having moved elsewhere. In the illustrated example, the portabledevice of user 6402 receives signals from the same wireless networkaccess points 6404 a-6404 d and obtains new network access pointinformation.

However, though the user is in the same tile, the new network accesspoint information may differ from the network access point informationpreviously stored in tile 6610 (e.g., 6606 in FIG. 66 ). Changes mayresult from the user being at different locations with a tile whendifferent wireless scans are performed. Alternatively, or additionally,changes may result from changes in propagation conditions for wirelesssignals, changes in the wireless access points or other causes. Bymerging new wireless information with previously collected information,the wireless information may be more stable and therefore more effectiveas a wireless signature for comparison with other wireless signatures.

In the illustrated example, the new network access point information ismerged with the previously stored network access point information toproduce merged network access point information 6706, which may bestored in the same tile 6610 with the same persistent locationinformation 6608. In the illustrated embodiment, the previously storedinformation is replaced with the merged information, such that thewireless information stored in association with each persistent posereflects the most recent wireless scan.

Producing the merged network access point information may, in someembodiments, comprise taking an average of previously stored signalstrength indicators and new signal strength indicators associated withthe access point identifiers. The averaging may be computed as a rollingaverage, for example. Producing the merged network access pointinformation may alternatively or additionally comprise replacing somestored network access point information with some, all, or none of thenew network access point information. In the illustrated example, theRSSI values indicated in boldface in the merged network access pointinformation 6706 represent an average of the RSSI values in thepreviously stored network access point information 6606, and new RSSIvalues obtained from the network access points.

Other processing may alternatively or additionally be used to improvethe stability of wireless signatures or to otherwise format theinformation for efficiently comparing wireless signatures. FIG. 68illustrates the user 6402 moving further within the 3D environment. Inthe illustrated example, the portable device is no longer in range ofthe wireless network access point 6404 a, but receives signals fromnetwork access points 6404 b, 6404 c, 6404 d, and 6404 e. In someembodiments, the network access point information collected by theportable device may be filtered before being stored.

In the example of FIG. 68 , the network access point information 6806collected from the wireless network access points 6404 b-e while theportable device is within tile 6810 is shown as new network access pointinformation 6807. The information 6807 may be filtered before beingstored. The new network access point information may be filtered basedon signal strength, for example. In some embodiments, the type ofnetwork access point or other pieces of information comprising thenetwork access point information may be criteria for filtering. In FIG.68 , an example of an access point identifier to be filtered due to alow signal strength value is shown in boldface in network access pointinformation 6807. In this example, the RSSI value of 3 associated withthe wireless network access point 6404 e in new network access pointinformation 6807 is below a threshold and is filtered out. Accordingly,the BSSID of wireless network access point 6404 e does not appear innetwork access point information 6806.

FIG. 69 illustrates an example of localizing a map from a portabledevice within another map based on the network access point information,according to some embodiments. In FIG. 69 , portable device map 7002 isto be localized against a stored map 7004 of a plurality of maps whichmay be stored, for example, on a remote computing device. In someembodiments, the portable device map may be a tracking map created bythe portable device. In some embodiments, the plurality of stored mapsmay be canonical maps representing previously mapped environments, suchas are stored by a localization service as described above. The portabledevice map and stored maps may have multiple tiles, as described inconnection with FIGS. 64 through 68 , with associated locationinformation and network access point information, serving as wirelesssignatures.

The localization of a portable device map with respect to the storedmaps may begin by selecting a subset of candidate maps and a subset oftiles within each map for comparison as part of a localization attempt.One or more filter criteria may be applied to select a subset of thestored maps as candidate maps. Similarity of wireless signatures may beused as one such filter criteria.

In the illustrated example of FIG. 69 , the network access pointinformation of tile 7006 in portable device map 7002 is similar to thenetwork access point information stored in tile 7008 of stored map 7004.Based on this similarity, the map 7004 may be selected as a candidatemap. Moreover, tiles 7006 and 7008 may be selected as candidate tiles. Alocalization attempt may initially be limited to attempting to localizethese tiles with respect to each other. If these tiles cannot belocalized, localization may be attempted between other pairs of tiles.The pairs of tiles may be selected in decreasing order of similarity.Alternatively, or additionally, even if tiles 7006 and 7008 can bealigned with a sufficiently low error that that they may be deemed to belocalized, localization may be attempted with respect to other pairs oftiles, which may be selected in decreasing order of similarity betweenthe tiles of the pairs. Additional data from localizing other pairs mayimprove the accuracy of location of the maps with respect to each other.Alternatively, or additionally, localization of other pairs of tiles maybe performed to identify additional maps covering all or a portion ofthe same area as map 7002.

In some embodiments, similarity of wireless signatures may be based onJaccard similarity. Network access point information of the selectedportable device map tile and the stored map tiles may be compared bycomputing a Jaccard similarity between the list of BSSIDs and respectiveRSSI values stored with the portable device map tile and thecorresponding information of the stored map tiles. Other algorithms andheuristics for comparing network access point information mayadditionally or alternatively be employed in order to compare thenetwork access point information of the selected portable device maptile to the network access point information of the stored map tiles.

In the illustrated example of FIG. 69 , candidate tile 7008 of storedmap 7004 is selected to be the most similar compared to the selectedtile 7006 of the portable device map 7002. In this example, theselection may be based on the similarity between the network accesspoint information 7010 associated with portable device map tile 7006,and the network access point information 7012 of candidate tile 7008 ofstored map 7004. In some embodiments, multiple candidate tiles may beselected in the canonical map.

Identifying maps with similar tiles may be done as a preliminary step toadditional processing, such as to merge maps and/or to localize aportable device with respect to shared coordinate frame. According tosome embodiments, a portable device map may be localized within a storedmap starting with the candidate tile or tiles selected based on thecomparison of network access point information. The localization processis described in detail at least in connection with FIGS. 23, 34, 44, 45,46A and 46B above. It should be appreciated that the localizationtechniques described in this subsection may be used in conjunction withany of the other methods for localization described herein.

In some embodiments, when localizing a device with respect to one ormore stored maps, it may not be required to compare the entire trackingmap with respect to the stored maps. The current tile, in which thedevice is currently located, for example, may be localized with respectto tiles of the stored map. The tiles of the stored map to select ascandidates with which to attempt localization may be selected based onsimilarity of wireless signatures. Alternatively, or additionally, a mapmay have multiple hierarchical divisions, and wireless fingerprints maybe associated with any level of the hierarchy, such that a selection ofa map based on a wireless fingerprint may result in a selection at anylevel of the hierarchy.

A map, for example, may be subdivided into areas, which in turn may bedivided into tiles. The wireless fingerprint of any tile within an areamay be used in selecting the area as a candidate map. Alternatively, oradditionally, the wireless fingerprints for multiple tiles within thearea may be aggregated into a combined fingerprint for the area.Aggregation may be performed, for example, by forming a list of BSSIDsthat appear in any tile and averaging the RSSI values for the BSSIDsthat are in the fingerprints of more than one tile.

Alternatively, or additionally, each tile may contain multiplepersistent points, such as multiple PCFs. Each such persistent point mayhave its own wireless signature. One or more PCFs may be selected aspart of the candidate map selection based on their wireless signatures.

Moreover, it is not a requirement that the selection of tiles in storedmaps lead to a localization attempt with respect to any portion of thetracking map. In some embodiments, for example, position information forlocalization with a shared map may be derived from current image datarather than from the tracking map. Nonetheless, the wireless signatureassociated with the tile in which the portable device is currentlylocated may be used to select tiles of the stored map as candidates forlocalization.

In some embodiments, localization based on the network access pointinformation comparison may comprise computing a transformation between aselected coordinate frame of the portable device map and a coordinateframe of the stored map being localized into. In some embodiments thecoordinate frames may be persistent coordinate frames (PCFs) and/orpersistent poses and/or an origin for a tracking map and canonical map.The selected coordinate frame of the portable device map may be thecoordinate frame associated with the tile selected for comparison ofnetwork access point information. The coordinate frame of the stored mapbeing localized into may be the coordinate frame associated with thecandidate tile selected as a result of the network access pointcomparison. In some embodiments, transformations for other coordinateframes may alternatively or additionally be computed based on thecomparison of network access point information.

Regardless of how the wireless signatures are used, techniques asdescribed herein may result in efficient generation of wirelesssignatures which may be available with low latency. FIG. 70 is a flowchart illustrating such a process according to some embodiments. Theprocessing described in connection with FIG. 70 may be performed on aportable device, in some embodiments, but may alternatively oradditionally be performed on one or more processors connected to theportable device over a network or other processors of the system. Theacts 7102 through 7108 are carried out by the portable device creatingthe map, while the other illustrated acts may be carried out, forexample, by a remote computing device, such as a server or a computingdevice comprising multiple computing devices in a cloud configuration.

In act 7102, the portable device obtains network access pointinformation at its location within the 3D environment. This act maycomprise obtaining BSSIDs and corresponding RSSI values for networkaccess points from which the portable device receives signals. In someembodiments, other network access point information may be collected,such as the names or types of network access points. This informationmay be acquired on a portable device equipped for Wi-Fi by a scanperformed by the Wi-Fi chip on the device. A scan may be triggered byany one or more conditions, discussed in greater detail below inconnection with element 7112.

In act 7104, the portable device may optionally filter and process thenetwork access point information collected in act 7102. The filtering orprocessing act may comprise dropping network access point information.For example, BSSIDs may be filtered based on the corresponding signalstrength values, or based on exclusion criteria of BSSIDs. Exclusioncriteria may be based, for example, on the BSSID name. Names containingthe term “phone” or other terms that suggest a portable access point maybe excluded. Similarly, access points that are not discoverable may beexcluded, as may access points with any other characteristics that mayindicate an access point that may not be detected by another deviceoperating in the same space. In some embodiments, filter step 7104 mayfilter out all but a predetermined quantity of access point information.For example, all but the three BSSIDs with the highest signal strengthvalues may be filtered out of the network access point information.

Other methods of processing the network access point information, suchas normalizing the network access point information or expressing thenetwork access point information in a different format for furtherprocessing or transmission, may additionally or alternatively beemployed.

In act 7106, a persistent point is selected to represent the location ofthe portable device. In some embodiments, the selected persistent pointmay be a persistent pose or PCF that is closest relative to the portabledevice in a map to which the portable device is localized.Alternatively, or additionally, a selected persistent point may be otherinformation representing the location of the portable device.

However, in the example of FIG. 70 , the persistent point may be apersistent pose in a tracking map of the device. In act 7108 a, in someembodiments, a new tile may be added to the tracking map if no data hasalready been stored for the current location of the portable device. Inother embodiments, an empty tile may be created and the new persistentpoint and corresponding data may be added to the empty tile. The newtile may include a persistent point of act 7106, and the network accesspoint information of acts 7104 and 7102.

Alternatively, in act 7108 b, the network access point information ofacts 7104 and 7102 may be merged with network access point informationalready associated with a tile in the tracking map. In some embodiments,this may comprise averaging the RSSI values associated withcorresponding BSSIDs in the network access point information. In someembodiments, this may alternatively or additionally comprise replacingthe stored network access point information with the new network accesspoint information or, conversely, retaining the stored network accesspoint information and discarding the new network access pointinformation. The new network access point information might be discardedrather than merged, for example, if it fails certain quality criteria,such as it deviates by a wide margin from previously collectedinformation or has very low RSSI values for all network access points,indicating the possibility of a reception problem.

After the data has been stored in act 7108 a or 7108 b, the portabledevice may take no further action with respect to forming wirelessfingerprints until a new network access point scan is triggered. Examplecriteria for a new scan being triggered are shown in acts 7110 a through7110 c. As illustrated, a new scan may be triggered based on a distancetraveled by the portable device since the previous scan exceeding athreshold (7110 c). Distance traveled may be determined by hardwareand/or software components of the device. The device, for example, mayinclude an IMU or GPS hardware that provide an indication of location orposition that may be used to determine when a threshold distance hasbeen traveled. Alternatively, or additionally, a device forming atracking map from a sequence of captured images may determine, based onrelative position of the device within the map, distance traveled.

In other examples, a new scan may be triggered by an amount of timepassing since a previous scan (7110 b). For example, a scan may betriggered if a scan has not been performed in more than a thresholdamount of time, which might be 20 seconds or 60 seconds or any value inthe range be 20 and 60 seconds, for example.

In other examples, an update in the network access points, such as aBSSID change, may trigger a new scan (7110 a) and/or may trigger thewireless hardware to send results of a scan.

Although these acts need not occur on the portable device, it should beappreciated that in some embodiments the portable device itself maytrigger a new scan according to acts 7110 a, 7110 b, or 7110 c. A scanmay also be triggered automatically for other reasons than thoseillustrated in FIG. 70 . For example, other components executing on thedevice may command the wireless chipset to perform a scan for reasonsunrelated to maintaining wireless signatures. In some embodiments,whenever a scan is performed, the wireless components may output anindication that scan data is available, which may then be used forupdating wireless signatures such that information on wireless networkaccess points may be pushed from the hardware without an express requestfrom components of the device constructing the wireless fingerprint.

Regardless of the specific mechanism that triggers the scan, in act7112, a new network scan is triggered. The process then proceeds to act7102, as described above.

It should be appreciated that the techniques described in thissubsection may be used in conjunction with the other techniquesdescribed herein. For example, the maps involved in the localizationprocess described in this subsection may undergo a filtering process asdescribed in conjunction with FIGS. 28 through 34 . As shown in FIG. 28, the filtering process may include a Neighboring Area Filter, a Wi-FiFingerprint Filter, a Key Frame Filter, or any of the other filtersdescribed in this application. As further shown in FIG. 28 , alocalization process may follow the filtering process. In someembodiments, this localization process may utilize the network accesspoint comparison technique for localization described in thissubsection.

Further, it should be appreciated that wireless fingerprints may be usedfor comparison of maps or selection of maps representing a particularlocation in the physical world, regardless of use of the selected maps.Techniques as described in this section are not limited to use in alocalization process. Wireless fingerprints, for example, may be used aspart of map rank process as described above. Alternatively, oradditionally, wireless fingerprints may be used to select mapsrepresenting the same or overlapping regions for a map merge, also asdescribed above.

Geo-Location Enhanced Map Ranking and Localization

As discussed herein, localization is a process to determine atransformation between one map and another map. A local map of a crossreality device may be localized to a canonical map, for example, so thatinformation on the location of virtual content in the canonical mapcoordinate frame can be related to, and rendered by, the cross realitydevice. Localization may be performed on a device (e.g., which mayreceive a set of canonical maps for localization), or by a remotelocalization service (e.g., which may store sets of canonical maps). Ineither implementation, localization may entail searching for matchesbetween sets of features in local and canonical maps, which may becomputationally intensive.

The localization process may be made more efficient by filtering, basedon location metadata, a universe of canonical maps against whichlocalization may be attempted. Location metadata may be collected andstored with the canonical maps and may also be associated with thelocation information sent from the portable device. In variousembodiments, location metadata may include geo-location data derivedfrom a component of a portable device (e.g., GPS coordinates), Wi-Fifingerprints, and/or information on prior localization results. In someembodiments, the location metadata that is available will vary fromdevice to device and may also vary based on connectivity, interference,current location, among other options. In some embodiments, a componentthat selects a subset of maps for localization attempts may determinewhich filtering criteria to apply based on available location metadata.

A similar approach for selecting a set of candidate maps for comparisonmay also be employed in connection with map ranking or otherpreprocessing to select a set of canonical maps prior to a mergeprocess. Map merge similarly entails comparison of location informationfrom a device against a set of maps in an attempt to identifycorresponding sections. In this case, the location information from theportable device may be in the form of a tracking map. Nonetheless, thecomparison of the location information in the tracking map to a set ofmaps may similarly be more efficient by using location metadata toreduce the number of candidate maps used in such a comparison.

Various embodiments utilize available location metadata to filter storedcanonical maps so that a filtered set of maps can be analyzed to matchone or more canonical maps to location information from a local device.For example, various embodiments may employ geo-location data to filtercanonical maps and limit the computational burden of matching duringlocalization and/or improve the accuracy of a resulting match. Otherembodiments may prioritize types of location metadata and apply ahierarchy to available location metadata to improve localization. Forexample, location metadata may include information on priorlocalization, geo-location, and/or Wi-Fi fingerprints, and the systemmay prioritize operations with prior localization information over othertypes of location metadata. In other embodiments, prioritization mayinclude exclusion or different weighting of non-prioritized locationmetadata types.

FIG. 74 is an example process 7400 that may be executed as part of localor remote localization that utilizes location metadata. Events thattrigger localization are not illustrated in FIG. 74 , but the processmay be performed in response to events that trigger localization asdescribe elsewhere, herein. Further, though not expressly illustrated inFIG. 74 , other processing may precede or follow the acts illustrated inFIG. 74 . For example, similar to the approach discussed with respect toprocess 6200, process 7400 may optionally be preceded by new sessionoperations for a device (e.g., 6202-6206 of FIG. 62 ).

Process 7400 may be performed after location metadata has beenassociated with some or all of the canonical maps in a universe of mapsused for localization. In some embodiments, location metadata may beadded to canonical maps as devices interact with an XR platform, suchthat maps and associated location metadata are developed, updated and/orcreated as part of localization, map merge operations, and/or map selectoperations as discussed herein.

Process 7400 may begin at 7402 with the receipt of a request to localizea device to a stored map, which may be a map in a set of canonical maps.In the illustrated example, process 7400 may be performed on alocalization service in the cloud and the localization request may bereceived over a wide area network from a portable device. However, thelocalization service may be executing in whole or in part on theportable device or in whole or in part on other computing devices.

The localization request may be based on location information in a localcoordinate frame for the portable electronic device to be localized.According to some embodiments, localization requests also may identifylocation metadata generated, stored, or captured by or for the portabledevice. The device may execute any of the map building and/orenvironment information collection functions discussed herein to acquirethat metadata. The location metadata may be included with thelocalization request. Alternatively, or additionally, the locationmetadata may be maintained by or accessible to the localization serviceand the localization service may access the location metadata based oninformation in the request. For example, the localization service maystore information on each active device, including its position based ona prior localization, and may access this information based on a deviceidentifier in the localization request.

By making the location metadata available for use in connection withprocessing a localization request, a cross reality platform mayincorporate location metadata into localization optimizations. Further,the platform may build location metadata into canonical maps based onlocation metadata communicated with localization requests. According tovarious embodiments, a cross reality platform may also create, maintain,and/or update a geo-location database linking canonical maps to certainlocation metadata, such as geo-location information. Such a database maymake the selection of candidate maps highly efficient, as thegeo-location database may be referenced to quickly identify candidatestored maps to use in processing a request that incorporates locationmetadata.

In various embodiments, the request may include one or more copies of aspecialized data structure that aggregates location information (e.g.,persistent location information, persistent pose, and/or featuredescriptors, etc.) captured in a device's 3D environment and thatcombines the location information with location metadata. In someexamples, a posed feature rig (“PFR”) is employed as the specializeddata structure that is used to aggregate location information andlocation metadata from the device's 3D environment. The PFR may includeposed feature descriptors, such as those that are described above inconnection with FIG. 63 , which provide location information. One ormore pieces of location metadata, associated with the physical worldlocation of the posed features may be stored associated with the posedfeature descriptors. The location metadata may include, for example,wireless fingerprints, geo-location information which may be expressedas GPS coordinates or geo-hash values, or information on priorsuccessful localizations. The metadata may be derived for the locationin which the images that gave rise to the features represented by thelocation information were captured. For example, the posed features maybe associated with a persistent pose in a tracking map for the portabledevice and the wireless fingerprint may be one stored with thepersistent pose of the tracking map. As another example, the locationmetadata may be geo-location information obtained by calling an API ofthe operating system of the device, and the value may be a value read atthe time the image frame from which the features were extracted wasprocessed. The PFR may alternatively or additionally include any of theinformation described herein as transmitted with a localization requestand/or used for localization.

As described herein, a portable device may buffer multiple such datastructures, collected at periodic intervals or in response to events, sothat they may be processed together as part of a localization request.Doing so, for example, increases the likelihood that at least one suchdata structure will be matched to a canonical map and/or increases theaccuracy with which the device location can be computed. Such bufferingmay be similarly applied in connection with location information forwhich location metadata has been associated and the request at act 7402may include multiple PFRs, in some embodiments.

Regardless of the exact structure of a request for localization, a setof candidate maps may be selected. In this example, process 7400includes a subprocess 7450 for selecting from a universe of maps, asmaller set of maps that are candidate maps for attempting localization.Subprocess 7450, though described in connection with localization, mayalso be used as part of a map rank process or a map merge process. Ifused for other processes, the received location information may beformatted differently. For example, rather than a PFR, locationinformation for a map merge may be formatted as a tracking map.

At act 7404, it is determined whether a localization hint is availablefor use. The hint may be based on the location metadata associated withthe request, and may be generated by finding from among the universe ofcanonical maps canonical maps with the same or sufficiently similarlocation metadata to expect that the selected candidate maps representan area overlapping with a location defined by the location informationin the localization request. In some embodiments, a localization hintmay be, or may be derived from, prior successful localizationinformation, Wi-Fi fingerprint data, geo-location data, and/or GPS data.In various examples, any location metadata might be used as alocalization hint if it can be compared to available location metadataassociated with stored maps.

According to various embodiments, if a localization hint is notavailable, 7404 NO, subprocess 7450 may continue at 7408 with filteringof available canonical maps based on content of the maps as discussedabove. If localization hints are not available, 7404 NO, localizationprocessing may continue in a similar manner as discussed with respect toFIG. 62 and process 6200.

If a localization hint may be used, 7404 YES, subprocess 7450 continueswith resolving localization hint priority at 7406. In scenarios in whichmore than one type of location metadata is available, resolving prioritymay determine which type is likely to be the most effective atidentifying candidate maps that represent the location of the portabledevice. In some embodiments, information associated with priorsuccessful localizations may be given the highest priority. In variousimplementations, selecting candidate maps in the location determined bya recent, prior successful localization may provide the highestlikelihood, relative to other location metadata, of identifyingcandidate maps that will contain the current location of the portabledevice. In further examples, prior successful localizations may beignored or given a low priority relative to other types of locationmetadata if too much time has passed between a current request and aprior successful localization. In addition, or in the alternative, priorsuccessful localization may be ignored or discounted if the requestingdevice is determined to have moved too great a distance from a priorlocation. According to some embodiments, information on prior successfullocalization is captured by a device and included in a request forlocalization (e.g., as part of any specialized data structure (e.g.,PFR)) and/or communicated separately from the data structure. In someexamples, the requesting device may manage invalidation of priorsuccessful localization information, and if invalidated, suchinformation may not be communicated as part of a localization request.

According to some embodiments, a device may be configured to suppresssending of prior localization information in some scenarios, such as ifthe device has moved a threshold distance after successful localizationand/or if a threshold amount of time has passed. If prior localizationinformation is not available, resolving priority at act 7404 may resultin selection of another type of hint or proceeding without a hint. Inthis example, the process may select between a hint based on a wirelessfingerprint or geo-location data. For example, a wireless fingerprintmay be collected by a portable device in which an application executingon the device can access device hardware, such as a Wi-Fi chipset.Alternatively, or additionally, geo-location data may be obtained by anapplication executing on the device via an API provided by an operatingsystem on the device. In that scenario, an operating system utility mayaccess device hardware, including for example a GPS chipset on thedevice, to generate the geo-location information.

Though not illustrated in the example of FIG. 74 , different oradditional sources of location metadata may be considered in theprioritization process. For example, if an application executing on adevice has access to a GPS chipset directly, GPS data from the chipsetmay be used directly to obtain a hint for the process of selectingcandidate maps. Also, though not illustrated, the selection may be basedon information in addition to the type of metadata. For example, whereGPS data is available, its priority may be based on locationinformation. GPS data may be given priority over a Wi-Fi signature, evenif both are available, when other data indicates that the portabledevice is operating out of doors, while a Wi-Fi signature may be givenpriority when other data indicates that the portable device is operatingindoors. Further, though process 7400 is illustrated as selecting onlyone type of hint, in some embodiments, when multiple types of metadataare available to generate a hint in the map selection process, the typesof metadata may be used conjunctively or disjunctively to select a setof candidate maps.

Regardless of the type of hint selected at act 7406, subprocess 7450 maycontinue to act 7408 to filter the universe of maps based on theselected location metadata. The universe of maps, for example, may be adatabase of canonical maps maintained by a localization service. Inother embodiments, filtering at 7408 may be executed against a set ofalready filtered maps. In that sense, the universe of maps in process7400 represents the collection of maps that is the starting point forprocessing as shown in FIG. 74 .

If prior successful localization information is selected for generatinga hint in the map selection process, subprocess 7450 may use thelocation prior to filter available canonical maps to those that arelikely to match a device's local map at 7408. The filtering operation(s)at 7408 may limit a universe of canonical maps to likely candidatesbased on proximity to the location identified in a prior successfullocalization. For example, a prior localization may have resulted in atransformation between a persistent coordinate frame in a canonical map.That canonical map may be selected as a candidate map. Where thecanonical maps in the database have location information associated withthem, other maps that depict locations that can be determined torepresent regions of the physical world near the location in the mapwhere a prior localization succeeded, may also be included in the set ofcandidate maps.

Similarly, if localization is performed based on a segment of acanonical map, such as one or more tiles, the hint provided by a priorsuccessful localization may guide the selection of one or more suchsegments.

If prior localization information is not available, discounted, and/orignored, hint priority may result in selecting a Wi-Fi fingerprint asthe location metadata with the next highest priority. For example, arequest for localization may include Wi-Fi fingerprint information, andthe Wi-Fi fingerprint information may be employed to filter the universeof canonical maps at 7408 and/or further filter a set of canonical maps.

Selection of candidate maps based on such wireless fingerprint metadatamay be as described elsewhere herein. Alternatively, or additionally,the map selection techniques as described herein may be modified basedon the location hints applied. As an example of such a modification,each type of location metadata may have an accuracy associated with it.A location prior has uncertainty associated with the possibility thatthe portable device has moved since the prior location was determined.GPS, which may be the genesis of geo-location data from an operatingsystem, may have an accuracy, for example 10 feet for a device operatedoutdoor or 50 feet when the device is operated indoors. Regardless ofthe source of uncertainty, candidate maps (or segments of maps) may beselected based on their proximity to a location within the zone ofuncertainty around the location indicated by the hint. As a result, insome embodiments, the number of maps, or map segments, in the set ofselected candidate maps may vary on accuracy of the location metadataused for a hint.

In scenarios in which location prior and Wi-Fi fingerprint informationis unavailable or not used, geo-location information from a deviceoperating system may be used to provide a localization hint. Forexample, process 7400 may proceed at 7406 based on determining onlygeo-location data is available for a given request, and filtering thesets of canonical maps is executed based on the geo-location informationreceived with the request for localization at 7408.

The illustrative embodiment is based on a relative priority for locationmetadata which prioritized valid prior location information over Wi-Fisignatures, which in turn are prioritized over geo-location dataobtained from the device operating system. Such a prioritization schememay be determined empirically based on impact on efficiency forlocalization and/or map merge. In other embodiments, otherprioritization schemes may be applied, such as because other locationmetadata is available and/or available location metadata has differentaccuracy, for example.

According to some embodiments, location metadata associated withcanonical maps may be maintained for filtering the canonical maps forlikely candidate maps based on location metadata associate with alocalization request. The metadata may be stored in a way thatfacilitates rapid selection of canonical maps. For example, one or moretypes of location metadata may be converted to geo-hash values andstored for respective locations associated with canonical maps. Invarious embodiments, the geo-hash values may provide a quicklysearchable index into the universe of candidate maps for locationmetadata that can similarly be converted to a geo-hash value. For aprior determined location, the location may be represented as a geo-hashvalue or world coordinates, such as latitude and longitude, that can bereadily hashed to create a geo-hash. Geo-location information may alsobe provided in such a format that can be readily hashed. Other metadata,such as a wireless signature may be converted to a geo-hash, such asusing a look up in a database of wireless access point identifiers andassociated geographic location.

In embodiments in which such an index is available and location metadataassociated with a localization request may be converted to a geo-hash, asearch of the index of geo-hash values may be performed. The searchresults from the geo-hash query provide a set of candidate canonicalmaps. That set of canonical maps may be further filtered (e.g., at 7408)and/or analyzed before further processing. In some embodiments, a set ofmaps may also be filtered on different criteria prior or subsequent toexecuting a geo-hash query. For example, map id, area id, etc., may alsobe used to further filter or pre-filter sets of maps, and, for example,pre-filtered sets of maps may then be queried based on geo-hash values.

In another example, a geo-hash query may be used to identify locationswithin respective maps, and may also provide candidate areas withincanonical maps. In one example, candidate areas can be specified bytiles within a map. In some embodiments, a map may be segmented intotiles, as discussed above, and each tile may encompass persistentlocation information (e.g., persistent pose and/or persistent coordinateframe, etc.).

For location metadata that cannot be readily converted to a geo-hash,other comparison techniques may be employed to select, from the universeof canonical maps, those that have values of location metadata similarto that provided with the localization request. Selection based onJaccard similarity, for example, was described above. In variousembodiments, any combination of filter steps and any order of filteringmay be executed to facilitate identification of a filtered set of mapsand/or areas within one or more maps on which to localize.

Regardless of the specific technique applied to select the set ofcandidate maps, processing may proceed to act 7410 where attempts aremade to match the location information provided with the localizationrequest to a location within a map of the filtered set of canonicalmaps. In an embodiment as described in FIG. 74 in which locationinformation is formatted as a PFR, localization processing may entailcomputing transformations that relate a set of feature points in the PFRto clusters of feature points in the set of candidate maps. Localizationmay be considered successful upon identification of a transformationthat results in a match between the set of features in the PFR and in acandidate map with an acceptable level of error. Techniques, such asdeep keyframe descriptors as described herein, may be used to facilitatefinding a match between feature sets. Various embodiments oflocalization processing are described herein, such as in connection withFIGS. 23, 34, 44, 45, 46A-B, 62, and 69 above, and may be used inprocess 7400.

If no suitably matching set of feature points is found for one of thePFRs sent with the localization request, localization may be attemptedwith features in another of the PFRs. Other actions also may be taken ifno suitably matching set of features are identified, such as expandingthe set of candidate maps.

If the search for a matching set of features results in identificationof a matching set of features, the transformation that led to thatmatching set of features may be returned as the localization result atact 7412. That transformation may indicate a correspondence between aselected coordinate frame of the device's map and a coordinate frame ofthe stored map containing the matching set of features. In someembodiments the coordinate frames may be persistent coordinate frames(PCFs) and/or persistent poses and/or an origin of a tracking map or ofa canonical map. The selected coordinate frame of the device, forexample, may be the coordinate frame associated with the tracking map ofthe device. The coordinate frame of the stored map being localized intomay be a persistent coordinate frame within a candidate tile selected asa result of the search in 7410. Such transforms enable the requestingdevice to position and/or display virtual content in its own coordinateframe even though information on the virtual content has been stored inassociation with a canonical coordinate frame. Once computed, atransform or, if more than one matching set of features is identifiedresulting in generation of multiple transformations, a table oftransforms may be communicated at 7412, for example, to a devicerequesting localization.

In further embodiments, the steps of process 7400 may be combined,executed in different order, and/or some steps may be omitted.Discussion of the execution of process 7400 is described with respect toexample location metadata type and priority. In other embodiments,additional location metadata may be employed to use in filtering maps,selecting tiles, etc., and different priorities may be assigned tovarious location metadata or developed over time.

According to some embodiments, a cross reality platform may beconfigured to capture location metadata from respective devices that areconnected to it. That location metadata may be captured as part of a mapmerge process. A portable device may acquire location metadata for itscurrent location as it builds a tracking map. Accordingly, when thetracking map is provided as an input for a map merge process, thelocation metadata may be incorporated into a merged map. Alternatively,or additionally, successful localization in response to a localizationrequest that includes location metadata may provide an alternative oradditional source of location metadata for inclusion in a canonical map.

FIG. 75 illustrates an example of a portable device generating atracking map containing location metadata (e.g., Wi-Fi fingerprints,geo-location, GPS data, etc.) for use in localization hints or otherfunctions, according to some embodiments. In this example, a Wi-Fifingerprint, as described above, is shown in conjunction withgeo-location metadata. Some devices may collect both of these types ofmetadata, in addition to possibly other types of location metadata. Forexample, devices can capture location metadata from additional sensorsor systems in the devices 3D environment. In some embodiments, devicescan connect to and capture additional location metadata smart devicesaround present around a user location (e.g., home, shopping area, venue,etc.). However, in some embodiments, a single device may collect eitherWi-Fi finger prints or other geo-location data.

In FIG. 75 , a user 7502 with a portable device is shown in athree-dimensional (3D) environment containing wireless network accesspoints 7504 a through 7504 e. Wireless hardware on the portable devicemay be used to establish location metadata, and for example, todetermine a network access point identifier and signal strengthindicator value for each network access point for which a signal isdetected. According to some embodiments, wireless access data may alsobe used to determine geo-location for the device, which may be expressedin latitude and longitude as for GPS coordinates, for example. The knownGOGGLE geo-location API may be accessed to obtain the geo-locationinformation from wireless signals accessible by a device. In variousembodiments, generated or captured geo-location information may be usedto augment device generated maps of their environment.

As shown in FIG. 75 , the network access point identifier may be a basicservice set identifier (BSSID) and the signal strength indicator valuemay be a received signal strength indicator (RSSI) value. In someembodiments, the network access point information may be used to form aWi-Fi fingerprint, such as was described above in connection with FIGS.64-68 , for example. In some embodiments, other information about thenetwork access points may be collected in addition to or instead ofnetwork access point identifiers and signal strength indicators.

Location metadata may be stored in connection with locations of thetracking map. For example, location metadata may be stored inassociation with a tile 7510 of a map 7512 when the user device is in alocation corresponding to that tile. A respective user device maycapture and include network access point information and may alsocapture and include geo-location data 7509. The geo-location data may begenerated by GPS hardware on the device, through an operating systemAPI, or from another source, such as a GOGGLE geo-location API. In someembodiments, geo-location data may be stored as a separate geo-locationdata structure or may be integrated into the same data structure asother location metadata. For example, wireless information serving as awireless fingerprint 7506 may be stored in association with tile 7510 ofa map 7512 when the user is in a location in the physical worldrepresented by tile 7510.

Location metadata may alternatively or additionally be stored inconnection with other components of a tracking map. Persistent locationinformation may also be stored for tile 7510. Persistent locationinformation 7508, defining a persistent location, may be stored as adata structure in non-volatile memory within or connected over a networkto the portable device. In some examples, location metadata may bestored in or associated with this data structure. In some embodiments,the persistent location information 7508 may comprise a persistentcoordinate frame or persistent pose, as described above. In thisexample, location metadata in the form of wireless fingerprint 7506 andgeo-location information 7509 may be stored in a data structure thatstores persistent location information 7508 or that is linked to such adata structure.

In the illustrated embodiment, there is one persistent location pertile, such that metadata may be associated with either the persistentlocation or the tile. In embodiments in which there is not a one-to-onerelationship between tiles and persistent locations, the locationmetadata may be stored in connection with the tile and/or the persistentlocation. Different types of location metadata may be stored in the sameor different data structures. Wireless signatures may be stored inconjunction with persistent poses, for example, while geo-locationinformation may be stored in connection with tiles. Regardless of themap component for which the metadata is stored, as the user 7502traverses a space in the real world, collecting data that expands thetracking map 7512, the device may collect data about the user's locationas map components are added to the tracking map and/or updated in thetracking map. The location metadata may be captured as the portabledevice is building a tracking map, such that wireless information and/orgeo-location data may be captured and stored as new persistent poses arecreated. Tile 7518 may be added to the tracking map 7512 as the user7502 moves such that the user's device gathers information about anadditional location in the physical world. Tile 7518 illustrates newsignal strength values associated with movement of the user device andresulting change in proximity between the portable device and thewireless network access points 7504 a-7504 e. For tile 7518, the changein location of the user has caused the user to enter a space that wasnot yet mapped in the tracking map such that a new persistent pose iscreated and new persistent pose information 7516 is stored. Any newlocation metadata, for example new network access point information 7514and/or geo-location data 7517 may be stored with the new persistentlocation information 7516 in a new tile 7518 of map 7512 as illustrated.

Tile 7524 illustrates a result of the user 7502 moving further withinthe 3D environment. In this example, the portable device of user 7502receives signals from wireless network access points 7504 a, 7504 b,7504 c, and 7504 d, and captures geo-location information. New networkaccess point information 7520 and/or geo-location data 7523 may bestored with persistent location information 7522 or may be stored inconnection with tile 7524 of the map 7512.

Likewise, further movement may result in a further tile 7530 being addedto the tracking map, with additional persistent pose information 7528and location metadata, here network access point information 7526 andgeo-location information 7529.

According to some embodiments, location metadata may be captured atvarious times during development of a user device tracking map. Locationmetadata may be captured at different times for the same component ofthe tracking map. Additional location metadata for a map component, suchas a persistent pose or a tile, may be collected when a user remains inposition or within a certain distance of a position or returns to thatlocation at a later time. New location metadata may be aggregated withpreviously stored location metadata for a component. In someembodiments, for example, data values for respective data fields in ageo-location data structure may be averaged, expressed in ranges, ormerged, among other options. By merging new location metadata withpreviously collected information, the location metadata may be morestable and therefore more effective for comparison with other locationmetadata.

New network access point information may be merged with the previouslystored network access point information to produce merged network accesspoint information, as described above. Similarly, geo-location data maybe merged over time, replaced with newest data, and/or averaged andstored in association with persistent location information responsive tosubsequent data captures.

Producing the merged location metadata may, in some embodiments,comprise taking an average of captured information. The averaging may becomputed as a rolling average, for example. Producing the mergedlocation metadata may alternatively or additionally comprise replacingsome stored location metadata with some, all, or none of the newlocation metadata.

Other processing may alternatively or additionally be used to improvethe stability of location metadata or to otherwise format theinformation for improving localization operations. Filtering forexample, was described above for wireless network information.Similarly, other location metadata may be filtered. For example,geo-location data 7529 may also be filtered. In some embodiments,horizontal and vertical accuracy values provide information on theconfidence associated with a GPS reading and/or its associated accuracy.Where the accuracy values are too low, the information may be discardedwithout storing or averaging into previously stored values.Alternatively, or additionally, in some embodiments, the average ofmetadata values for the same location may be weighted based onrespective accuracy.

Once map data is captured by a portable device, the collectedinformation may be used to localize the portable device to a stored orcanonical map. In the illustrated example of FIG. 76 , a localizationrequest occurs while a user device is within tile 7606. A device may usetechniques as described above, such as processing images or otherinformation about the environment, to determine its location withrespect to a location in a tracking map. For generating a localizationrequest, the device may select as metadata to associate with the requestmetadata associated with a persistent location that the device hasdetermined is near its current location. The metadata may be themetadata stored with the persistent location or the metadata stored withthe tile containing that persistent location, for example.

In this example, the location metadata 7610 of tile 7606 in portabledevice map 7602 is similar to the location metadata 7612 stored in tile7608 of stored map 7604. Based on this similarity, applying subprocess7450 of process 7400 (FIG. 74 ), map 7604 may be selected as a candidatemap. Moreover, tile 7608 may be selected as a candidate tile. Alocalization attempt may initially be limited to attempting to localizetiles 7606 and 7608 with respect to each other. If these tiles cannot belocalized, localization may be attempted between tile 7606 and othertiles, such as those surrounding tiles 7608. The pairs of tiles may beselected in decreasing order of similarity.

In some embodiments, similarity of location metadata may be based onJaccard similarity, as was described above for wireless networkinformation forming a Wi-Fi signature. Similarly, similarity ofgeo-location metadata may be determined based on Jaccard similarity.Other algorithms and heuristics may be employed for comparing thelocation metadata associated with a portable device and locationmetadata of stored maps. For example, the location metadata may bemapped to a one-dimensional identifier, such as a geo-hash, that enablesdetermination of relative separation between two locations based on thedifference in value of this one-dimensional identifier.

In some embodiments, an XR platform may be configured to identifycandidate maps based on similarity between location metadata formultiple locations in the tracking map and a canonical map. Maps maythen be ranked based on a number of locations with matching locationmetadata information. For purposes of such a comparison, the locationsmay be deemed to match if the metadata values differ by less than athreshold amount. Such an approach may be used, for example, whenidentifying candidate maps into which to merge a tracking map.

According to some embodiments, identifying candidate maps with locationmetadata similar to a portion of a tracking map may be done as apreliminary step to additional processing, such as to merge maps and/orto localize a portable device with respect to a shared coordinate frame.According to some embodiments, a portable device map may be localizedwithin a stored map starting with the candidate tile or tiles selectedby location metadata analysis. The localization process is described indetail at least in connection with FIGS. 23, 34, 44, 45, 46A and 46Babove. It should be appreciated that the localization techniquesdescribed in this subsection may be used in conjunction with any of theother methods for localization described herein.

FIG. 77 shows an example architecture 7700 of a cross reality systemthat may provide immersive experiences to a variety of cross realitydevices and/or device types while preserving consistent visualizationand experiences regardless of the device being used.

As shown, various cross reality devices (e.g., 7702 and 7704) may accessa platform 7750. In this example, platform 7750 may be a cloud platformperforming functions as described herein, including cloud-basedlocalization and map merge.

One or more portable devices may communicate with platform 7750. Thosedevices may provide information on their environment to enablelocalization and/or to enable the platform 7750 to build and/or maintaina database 7712 of canonical maps. Although only two devices are shown,any number of cross reality devices, AR devices, VR devices, or otherportable devices may connect with the cross reality platform andparticipate in the immersive experiences generated.

According to some embodiments, different devices may interact with theplatform 7750 differently based on different capabilities. Differentdevices may have access to different types of location metadata. Forexample, devices native to the cross reality platform, which may includeMAGIC LEAP brand devices (e.g., device 7704), may be configured suchthat software on the device controlling augmented reality functionalitycan access a Wi-Fi chipset on the device. Such a device may have accessto Wi-Fi information to generate a Wi-Fi fingerprint. However, such adevice may not have a GPS chipset. A smartphone, such as an iOS device7702, conversely, may block software executing on the device fromaccessing its Wi-Fi chipset, but may make information from a GPS chipsetavailable through a geo-location API. Such a device when programmed tointeract with platform 7750, therefore, may have access to thatgeo-location information.

In some embodiments, devices that interact with a platform 7750 mayregister to access the platform, and part of that registration mayinclude identifying a device type or device capability and establishingwhat functions are to be used for the respective device. In someembodiments, the platform may determine if a device is or meetsthreshold requirements (e.g., similar capability of a MAGIC LEAP branddevice) or is classified as a “ML” device 7704 or is classified as an“XR” device 7702. Alternatively, or additionally, platform 7750 maydetermine which functions are performed for a device based on the typeof metadata provided by it. For example, if a device provides GPScoordinates of its location, platform 7750 may perform map selection forthat device based on geo-location, while map selection for a device thatprovides a Wi-Fi signature may be based on that metadata.

Some functions may be performed for all devices accessing platform 7750.For example, both types of devices may collect and communicateinformation on their local environment. In some embodiments, the devicesmay construct tracking maps and may communicate information on theirlocal environment based on the tracking maps. For example, the devicesmay be configured to communicate as part of a request to localize thedevice location information about the device, which may be in the formof one or more PFRs, with location metadata as described above. Some orall of the devices may be configured to transmit the tracking map toplatform 7750 to support map merge functions on the platform. In theexample of FIG. 77 , ML devices 7704 may transmit a tracking map for usein map merge processing, but XR devices 7702 do not.

The device tracking map may include embedded location metadata. In thisexample, location metadata includes geo-location information. In someexamples, a device's local map or tracking map may include geo-locationinformation associated with persistent locations of the local map, suchas a persistent pose in the local map. Other location metadata may becommunicated separately and/or as part of a data structure holding thegeo-location information. For example, ML devices 7704 may track andtransmit Wi-Fi signatures as part of the location metadata communicatedin connection with a request for localization and/or a tracking map formerging.

In some embodiments, platform 7750 may include a passable world module7708, which may perform some or all of the functions of a cloud-basedcomponent of a passable world model as described above. In the exampleof FIG. 77 , passable world module 7708 may be configured to interactwith multiple devices and manage execution of associated functions. Someexample functions, which may be performed at least in part based onlocation metadata received from the devices, include curation ofexisting maps to include the received location metadata, maintenance ofa geo-location database (e.g., 7714) associating location metadata tocanonical maps and/or tiles within the canonical maps, and map selectionand/or filtering, among other options.

In this example, PW module 7708 may manage interactions with portabledevices for localization and for map merging. In each case, informationreceived from the portable device may be used to select a set ofcandidate canonical maps. The selection of a set of canonical maps maybe performed by map select module 7710. Map select module 7710 mayperform a filtering process, such as subprocess 7450 (FIG. 74 ), whichis based on location metadata. For localization, the metadata may beassociated with a current location of the device. For map merge, themetadata may be associated with a tracking map or with multiplecomponents of the tracking map.

Accordingly, PW module 7708 may communicate the received location andlocation metadata to a map select module 7710. According to variousembodiments, the map select module 7710 may be configured to filter theuniverse of canonical maps to produce a set of candidate maps likely torepresent a portion of the physical world described by the locationmetadata. The universe of canonical maps may be stored in any suitablemedium, for example, in storage 7712.

As described above, in some scenarios, map select module 7710 mayidentify candidate maps based on similarity of Wi-Fi signatures receivedfrom the portable device to Wi-Fi signatures associated with maps instorage 7712. In some scenarios, the selection may be based onsimilarity of geo-location data. Platform 7750 may be configured forefficient selection of maps from map store 7712 based on geo-locationinformation. For example, platform 7750 may include a geo-locationdatabase 7714 for this purpose.

Geo-location database 7714 may be indexed on geo-hash values to speedprocessing. Table I illustrates an example of a record in geo-locationdatabase 7714 with field names and data types. Other embodiments can usedifferent field names and/or data types, and may omit or consolidatevarious fields of the example data structure.

TABLE I field name data type Id Integer Latitude Numeric longitudeNumeric Altitude Numeric heading_deg Numeric horizontal_accuracy Numericvertical_accuracy Numeric Geohash String map_id Uuid map_version Integerpp_id Uuid Provider String Timestamp Timestamp

In this example, a record may be stored for each geo-hash value computedfrom geo-location metadata associated with each canonical map in mapstore 7712. In embodiments in which the geo-location metadata isassociated with multiple persistent locations in a map, there may bemultiple geo-hash values for the map. Table I illustrates a file, namedpp_id, which may be used to identify a specific persistent locationwithin an identified map identified by a geo-hash value.

To select candidate maps based on geo-location information, map selectmodule 7710 may compute a geo-hash of geo-location metadata accompanyinga localization request or a request to merge a tracking map. Map selectmodule 7710 may then query geo-location database 7714 for records withsimilar geo-hash values. The query, for example, may request recordswith geo-hash values within a predefined range of that geo-hash value,or within a predetermined percent of that geo-hash value. As anotherexample, geo-hash prefixes may be used to return matching values.Alternatively, or additionally, the query may request a fixed number ofrecords with values closest to the geo-hash value.

As shown in Table I, a record from geo-location database 7714 mayidentify a map and/or a persistent location within a map. In embodimentsin which selection of candidate maps entails selecting a segment of amap, the identified persistent location may be used to select theappropriate segment. For example, a tile containing the identifiedpersistent location and surrounding tiles of the map may be identified.The identified maps may be used as a set of candidate maps, with orwithout further processing.

As an example of further processing that might be performed, additionalfields from the record may be used to impact the selection of map. Asanother example of other processing, the latitude, longitude, andaltitude fields may be used to confirm that the selected recordaccurately matches the geo-location metadata that was hashed to querygeo-location database 7714. Alternatively, or additionally, thetimestamp field may be used to remove from the set of candidate mapscanonical maps that are old and may be out of date. As another example,altitude and heading information may be included in a geo-location datastructure, which may also be used for confirming matches. Alternatively,or additionally, accuracy information may be used to compute a size of asegment of a matching map included in the set of candidate maps. Wherethe accuracy is lower, a larger segment of a map may be selected as acandidate. In embodiments in which canonical maps are partitioned intotiles, a number of tiles to at least encompass an area of uncertaintyaround the specified location may be included in the set of candidatemaps. Accuracy, for example, may specify as a radius around a locationrequired to achieve a specified probability (such as 98%) that theactual location falls within that radius. Accordingly, tiles thatrepresent a location within that radius of the specified location may beincluded in the candidate set of maps.

If a geo-hash index is not available, other searching techniques may beused to identify candidate maps. Brute force searching may be executed,for example, with geo-location data to determine distances from a devicelocation to stored maps and/or tiles within stored maps. In addition orin the alternative, geometry libraries may be used to provide efficientindexes and query operations for latitude/longitude data.

The selected set of maps may be communicated to other modules forfurther processing. When the selection of maps was made in response to arequest for localization, the set may be provided to localization module7716. Localization module 7716 may attempt to localize a device againsta map in the set of selected maps. Localization module 7716 may performprocessing as described above in connection with acts 7410 and 7412(FIG. 74 ) or other localization processing as described herein. Asdescribed in connection with act 7412, the result of a successfullocalization may be a transformation between a local coordinate frame ofthe device and that of a canonical map. That transformation may be sentto the local device.

In some embodiments, geo-location metadata may be sent to some devicesfollowing a successful localization. In the embodiment illustrated inFIG. 77 , ML devices 7704 do not generate geo-location metadatathemselves, for example, from GPS chipsets, but maintain geo-locationdata in their respective maps, based on, for example, geo-location dataobtain and/or derived from other processes (e.g., GOOGLE geolocationAPI, etc.). However, platform 7750 maintains, in connection withcanonical maps, geo-location metadata. Successful localizationestablishes a correspondence between a persistent location in a devicetracking map and a component of a canonical map. If that component ofthe canonical map has geo-location information associated with it,platform 7750 may return the geo-location information and the device maystore it in connection with the persistent location that was the basisof the successful localization. In the example of FIG. 76 , uponsuccessful localization of tile 7606 to tile 7608, geo-locationinformation stored in the location metadata 7612 may be transferred tothe device and stored as part of location metadata 7610. In this way,devices that do not generate geo-location information may obtain suchinformation.

In some embodiments, localization module 7716 may also be configured toupdate geo-location database 7714 and/or map storage 7712. For example,a successful localization to a location within a canonical map based ona request containing geo-location metadata indicates that the locationwithin the canonical map is identified by that geo-location metadata.Accordingly, the geo-location database 7714 may be updated with a recordindicating that the canonical map, or more specifically a locationwithin that map, is identified by that geo-location metadata. Similarly,metadata stored in connection with the matching location in thecanonical map may also be updated based on the location metadatareceived with the localization requisition. Such an update may be madeby updating map storage 7712.

Alternatively, or additionally, the PW module 7708 may manage updatingstored maps with location metadata and in particular geo-locationinformation based on map merge functionality discussed herein. In someexamples, the platform may include a map merge component 7718 configuredto execute various map merge functions discussed herein. The map mergeoperations may include any of the functions discussed herein withrespect to map merge, and may include operations to aggregate variouslocation metadata.

In the embodiment illustrated in FIG. 77 , platform 7750 receivestracking maps for map merge only from ML devices 7704. Accordingly,canonical maps are initially created only with Wi-Fi signatures aslocation metadata. Over time, however, as geo-location information isobtained and shared, it may also be incorporated into the set ofcanonical maps in map store 7712. For example, as XR devices 7702, whichsupply geo-location metadata with localization requests, performlocalization, geo-location metadata may be added to map store 7712.Geo-location information further may be propagated through the systemupon successful localization of an ML device 7704 to a map for whichgeo-location metadata is available and returned to the ML device 7704 asdescribed above. Alternatively, or additionally, geo-locationinformation may be incorporated into the system by converting otherlocation metadata, such as a Wi-Fi signature, to geo-locationinformation, such by utilizing a commercially available look-up betweenWi-Fi access point information and geo-location.

FIG. 78 illustrates an example process flow 7800 for incorporatinggeo-location data captured from devices into a geo-location database.Process 7800 may be executed by platform 7750, for example. In otherembodiments, process 7800 may be performed in whole or in part on adevice active on a cross reality platform. In yet other embodiments, theprocess may be performed in part on a device and in part on theplatform.

A device may capture information on its environment and sendlocalization requests based on image data captured or derived from its3D environment. As discussed above, a portable device may generatefeature descriptors that provide information on the location of theportable and communicate those descriptors in a request to localize theportable device to a stored map. In some embodiments, the portabledevice may also capture or accumulate location metadata to communicatewith a localization request. For XR devices 7702, that metadata mayinclude geo-location information acquired from the device operatingsystem. For ML devices 7704, that request may include geo-locationinformation, if that information has already been propagated to it fromplatform 7750.

According to some embodiments, process 7800 may begin at block 7802 withreceipt of a localization request from the device. That request mayinclude or identify location information and location metadata. In someexamples, the location information may be formatted as a PFR containingfeature descriptors. That PFR may also contain location metadata, whichmay be of any one or more of the types described herein.

At 7804, a localization hint may be generated to facilitatelocalization. As shown, in FIG. 78 , a localization hint manager 7806may be configured to generate a localization hint based on availablelocation metadata. In some embodiments, the localization hint manager7806 is configured to determine a priority of available locationmetadata and employ the information with the highest priority. Thatprocess may operate as described in connection with act 7406 (FIG. 74 ).Alternatively, or additionally, priority may be defined and/or assignedbased on analysis of localization accuracy.

Depending on the location metadata available, the localization hint isgenerated at 7804 by the hint manager 7806. In this example, the hintmay be generated by selecting a set of candidate maps based on theavailable location metadata with the highest priority. That processingmay be performed in accordance with the processing described inconnection with act 7408 (FIG. 74 ) or as otherwise described herein.

Once a hint is generated, localization may be performed at act 7808based on that hint, by attempting to localize against the selected setof candidate maps. Various operations to determine if a device may belocalized to a stored map are discussed above and any one or more ofthose operations may be performed at block 7808.

At decision block 7810, a determination is made as to whether thelocalization was successful. Successful localization may be determinedbased on correlation, above a threshold, between the locationinformation received with the localization request and a stored map.Alternatively, or additionally, any other operations described hereinfor assessing success of localization may be applied.

Upon successful localization, process 7800 may return a localizationresult at 7812, which may include one or more transforms between adevice coordinate frame and the coordinated frame of the matchedcanonical map. If the portion of the canonical map against whichlocalization succeeded includes get-location information as locationmetadata, that geo-location information may be returned to the device.

Additionally, once a successful localization is achieved, a new entry,reflecting geo-location information for the matched canonical map, maybe inserted into geo-location database 7816 at act 7814. That entry mayinclude geo-location metadata, which may be copied from the locationmetadata received with the localization request. Alternatively, oradditionally, the geo-location metadata may be derived from informationprovided with the localization request. For example, geo-locationinformation may be looked up for a Wi-Fi signature sent with thelocalization request.

According to some embodiments, if a localization operation fails 7810,the geo-location database may still be updated at block 7814. Suchprocessing may be used, for example, in a platform in which the set ofcanonical maps are initially formed without associated geo-locationinformation, but geo-location information is propagated from devicesinteracting with the platform. Such processing may accelerate thepropagation of geo-location information, which may in turn increase theefficiency of the platform.

For example, the geo-location database may still be updated at 7814, ifprior localization information is available for the device requestinglocalization. Upon a failure to localize, process 7800 may proceed toblock 7818 where a determination is made whether valid priorlocalization information is available for the device. The priorlocalization information may be stored by the platform as part of arecord for the device. Alternatively, or additionally, the priorlocalization information may be sent from the device as part of thelocation metadata for a localization request. Validity of the priorlocalization information may be determined based on one or morecriteria, such as passage of time since the last localization and/ordistance traveled by the device since last localization. In someembodiments, processing at block 7818 may be performed on the device,which may determine whether its prior localization result is valid andmay suppress sending it with a localization request if invalid.

If, as determined at block 7818 the prior localization is valid andthere is geo-location information associated with the priorlocalization, that geo-location information, along with the mapidentified in the prior localization may be used to add a record atblock 7814. Otherwise, the geo-location database is not updated whenlocalization fails and no valid prior localization information isavailable.

Geo-location database entries may include the information described inTable I, among other options.

Enhanced XR Device Compatibility with Remote Localization

As noted above, a cloud-based or other remote localization service mayoffer a number of advantages in an XR system, including conservation ofnetwork bandwidth and computational resources, while enabling multipledevices to present an immersive XR experience to multiple users.Techniques as described in this section may provide access by a widevariety of XR device types to remote localization functionality so as toenable shared experiences to users of multiple types of devices.

It should be appreciated that enabling a variety of XR device typesaccess to remote localization functionality is a challenging task. Thedifferent devices may have cameras with a wide variety of cameraintrinsics, including cameras having varying image resolution, focallength, angular field of view, and/or other characteristics. The devicesmay also employ widely varying hardware and/or software. In thisrespect, some XR devices may have head mounted displays and multiplecameras, as described above, while other may be handheld mobile devices(e.g., smartphones, tablet computing devices, e-reader devices, gamingdevices, etc.) or other type of portable computing device comprising acamera and/or a display. These devices may therefore operate differentlywhen performing functions needed to provide a shared user experience inan XR environment, for example, due to hardware and/or softwaredifferences between the various XR devices. Nonetheless, these multipletypes of devices may be configured to operate to provide a sharedexperience to their users by configuring each device to interact with alocalization service that provides localization to each device based ona set of maps.

An efficient implementation of an XR system that supports multipledevice types may leverage native AR components of the devices. Smartphones, for example, may have an augmented reality framework. Examplesof such a framework are ARKit, which is available for devices executingthe iOS operating system, and ARCore, which is available for devicesoperating the Android, Android NDK, Unity, Unreal and iOS environments.These frameworks, for example, may provide the software components toenable the device to present a live view of a 3D environment, capturedwith a camera on the device, on a display of the device. These softwarecomponents may also control the rendering of virtual content to overlayit on the display, in a defined position with respect to objects in the3D environment. These components may also control the capture of imagesfrom device cameras, build tracking maps from the images, and identifypersistent points that serve as anchors for virtual content. They mayalso provide interfaces through which applications may specify thevirtual content, and its location with respect to the anchors. Thesedevices, however, may not enable applications to access the Wi-Fichipset to obtain a Wi-Fi signature, but may provide an API throughwhich geo-location information may be provided.

An efficient implementation of a multi device type XR system may enablea subset of the native AR components to work with other XR systems, suchas those described above. In some embodiments, that implementation mayentail interface components, which may execute on the device, to obtainfrom the native AR components image information and/or other informationfrom which a request for localization services may be generated. Theinterface components may process the information from the native ARcomponents in a way that enables the localization service to provide anaccurate result and send the localization request. The interfacecomponents may format the response from the localization service suchthat it may be used by the native AR components to position virtualcontent on the device, positioned in a specified location with respectto the 3D environment. As any of multiple types of devices may beefficiently configured in this way, such an XR system may supportoperation of multiple device types providing a share user experience.

FIG. 71 depicts a representative system 7120 for providing an XR deviceaccess to remote functionality, here shown as a cloud-based, remoteservice. Representative system 7120 includes XR device 7150 and remoteservices 7130. In this example, the XR device 7150 may be a smartphone,tablet or other portable or non-portable electronic device that isprogrammed for XR functions, but might also perform other functions. Forexample, XR device 7150 may be any electronic device which is portableor non-portable (e.g., is intentionally not movable, such as to preventtheft of the device, and/or restricted in one or more degrees offreedom, such as to have less than six degrees of freedom) and which isconfigured to execute the iOS or Android operating system, or may be anAR, VR and/or MR device (e.g., a Vive device). It may include a camera,display and other components found in a portable or non-portableelectronic device, such as an IMU, GPS or wireless chipset.

XR device 7150 includes a native AR framework 7160, which in thisexample is not configured to operate with remote services 7130. Othercomponents, as described below, nonetheless enable device 7150 to bepart of an XR system providing cross reality experiences to multipleusers. Though FIG. 71 shows a single device configured for XRfunctionality, it should be understood that the any number and any typeof devices may be configured as illustrated in FIG. 71 to interface withremote services 7130, enabling multiple users, with multiple types ofdevices to share in an XR experience coordinated by XR system 7120.

In this example, remote services 7130 includes authentication/identityservice 7135, which authenticates and identifies XR device 7150, viacommunication with a corresponding authentication service 7165 on XRdevice 7150. Based on device authentication, remote services 7130 mayrespond to or refuse requests for services from one or more devices.Authentication may be based on an account status of a user of thedevice. Alternatively, or additionally, authentication may be based ontype of service requested and type of device making the request. Forexample, remote services 7130 may include a service that buildscanonical maps based on tracking maps supplied by one or more devices,as described above. Devices that contain cameras and processingcapability that yield tracking maps above a quality threshold may beauthorized to supply tracking maps for this purpose, while otherdevices, regardless of account status of their users, may be deniedaccess for this service.

Remote service 7130 also includes passable world (PW) cloud service7140, which communicates passable world information to XR device 7150via PW service 7170. This passable world information may include maps,persistent points such as PCFs or persistent poses, meshes, objects,planes representing the physical world, including, in some embodiments,some or all of the information maintained about a passable world aselsewhere described herein. PW service 7170 may also providelocalization services, also as described herein.

Components to communicate with any of the services contained withinremote service 7130 may execute on device 7150. Such components may beacquired from a developer of the XR system including remote services7130. In this example, authentication service 7165 and PW service 7170are components of an XR software development kit (SDK) 7155, which maybe provided to software developers preparing software to execute ondevices of the same type as device 7150. In this example, SDK 7155 isillustrated as resident in device 7150. One skilled in the art willunderstand, however, that such notation indicates that componentsderived from SDK 7155 are installed on device 7150, but that theentirety of the SDK may execute on a computer elsewhere than on device7150.

In this example, SDK 7155 also supplies components that interface withother components executing on device 7150. Those components includeperception service 7175 and XR API 7180. Perception service 7175 iscoupled to the XR device's native AR framework 7160, which may provideinformation relating to the device's interaction with the physicalworld, including camera images, its position, movement and/ororientation. The information provided through this interface may includedata acquired in the 3D environment of the device, including forexample, GPS (or other geographical location) information and data ondetected network access points, such as which may be used for GPS-and/or Wi-Fi-based localization.

Perception service 7175 may process this information and supply it to PWservice 7170, where it may be further processed and supplied to PW cloudservice 7140. This perception information may be processed, for exampleas described in greater detail below, to place it in a form that it willyield an accurate localization result for the device 7150. It should beappreciated that, though a representative embodiment is illustrated inwhich perception service 7175 and PW service 7170 are shown as separatecomponents, the functionality of these components may be performed inone component or more than two components. Accordingly, processing asdescribed herein on perception data performed on device 7150 may beperformed in either component or distributed over both components orotherwise architected.

PW service 7170 may also process results of localization servicesreceived from PW cloud service 7140. That processing may includeproviding the localization results in a format that they can be used bynative AR framework 7160 to render virtual content in a sharedexperience. As described above, localization services may provide atransformation between a local coordinate frame used by a device and ashared coordinate frame, reflected for example, in a canonical mapstored in the cloud. Applications providing a shared experience fordevices using the system may specify the location of virtual content inthe coordinates of the canonical map, and the transformation may be usedto enable a device to determine a location, with respect to its localcoordinate system in which this virtual content is to be displayed. Thetransformation, in this example, relates one or more canonicalcoordinate frames to the local coordinate frame of the native ARframework 7160.

In this example, the transformation may be provided, in any suitableformat, to an application engine 7185 and/or an application 7190supplying virtual content for rendering on a display controlled bydevice 7150. For example, the transformation may provide atransformation between a PCF, in a format used by cloud services 7130 torepresent locations in the 3D environment, into an anchor in a formatused by native AR framework 7160. Such a transformation may be applied,for example, in app engine 7185, to transform information specifying thelocation of virtual content generated by application 7190 into a formatthat may be supplied to native AR framework 7160 through its nativeAPIs. The transformation may be applied in reverse, for positioninformation from native AR framework 7160 being supplied to othercomponents implementing the XR system.

Applications 7190 may be configured to create or obtain virtual contentthat may be shared with other users. For example, multiple users mayplay a game in which the virtual objects, such as coins or other prizes,are specified to appear to all the users at locations distributed arounda 3D environment. Each user may have a game application on their devicethat receives specifications of the virtual objects, and theirlocations, which may be specified relative to PCFs or in other formatssupported by the XR system. These game applications may communicate witheach other or a common server to share a common description of all ofthe virtual objects, such that each application can receive thespecification for the virtual objects and provide commands to renderthose objects. Those communications may be in a format used by XR system7120.

In the example of FIG. 71 , these commands may be provided to native ARframework 7160, after being transformed to express positions in theformat of anchors of the native AR framework 7160. Conversely, theapplication may receive information from native AR framework 7160, suchas information indicating user interaction with the virtual content. Appengine 7185 may transform any position information contained with thoseindications from the format of native AR framework 7160 to a format usedby XR system 7120. Thus, users of multiple devices, even if thosedevices have native AR frameworks incompatible with XR system 7120, mayshare in the game experience.

FIG. 72 depicts a representative process 7200 whereby an XR device mayaccess remote localization functionality, in accordance with someembodiments. Process 7200 may be implemented within device 7230, usingsome or all of the components described above.

At the start of representative process 7200, in act 7210, images arecaptured by a camera of a device which depict the physical surroundingsof the device. Image capture may be performed in any of numerous ways,such as in the manner described above in relation to act 6204 of theprocess shown in FIG. 62 . In some embodiments, the images captured inact 7210 may be two-dimensional, but depict a three-dimensionalenvironment of the XR device at the time of image capture.

Image capture for providing perception information to support an XRexperience may be controlled, in this example, by native AR framework7160. The processing of those images for compatibility with other XRdevices may be performed in whole or in part within perception service7175 and/or PW service 7170. Accordingly, the captured images may besupplied to such components alone, or with other perception data.

The process then proceeds to act 7220, where a subset of the imagescaptured by the device in the act 7210 are selected as being suitablefor localization. An image may be selected as being suitable forlocalization based on any of one or more criteria. For example, in someembodiments, a captured image may be selected based upon an absence ofexcessive brightness and/or motion blurring in the image.

The presence or absence of these and/or other qualities in an image maybe determined in any suitable way. For example, excessive brightness maybe determined by an average pixel value for the pixels making up theimage above a threshold. The presence of motion blurring in an image maybe detected by (as examples) sensing motion of the device capturing theimage, such as with an inertial measurement unit; detecting, in animage, patterns which are characteristic of blur; and/or comparingsuccessive images in a sequence to determine a change of position offeatures from one image to the next, as an indication that the devicemoved too fast between successive image frames. Other techniques thatmay be alternatively or additionally used include computing a varianceof an image Laplacian and/or computing gradient derivatives or wavelettransforms, and detecting a range of values outside a rangecorresponding to images previously identified as suitable. In someembodiments, it may be determined that an image is unsuitable forlocalization if motion blurring in the image exceeds a predefinedthreshold amount of motion blurring. As a specific example, images witha Laplacian variance above 200 may be excluded.

Alternatively, or additionally, other criteria which may be used toselect, or conversely exclude, images may include the number of cornersdetected in the image. For example, at least 30 corners might berequired in selected images, or images for which native AR framework7160 indicates that tracking has been lost may be excluded.

Process 7200 then proceeds to act 7230, wherein pre-processing isperformed on the images selected in act 7220. Image pre-processing mayentail any suitable number and type of operations. For example, imagepre-processing may include sigma de-noise operations, lens shadingcorrection, gamma correction to address image brightness, and/or otheroperations. Operations may be performed in any suitable order andsequence.

In some embodiments, the goal of pre-processing may be to normalizevalues for one or more parameters of interest represented in pixels ofan image captured by the XR device with expected values for the sameparameter(s) for pixels of images captured by a benchmark device (e.g.,the wearable device 580, described above with reference to FIG. 4 ). Thereference device, for example, may be a typical device used inconnection with the XR system 7120. Maps and other information about thephysical world maintained by PW cloud service 7140 may have beencaptured by devices of the same type as the reference device.Alternatively, or additionally, images used to generate maps or otherinformation maintained by PW cloud service 7140 may have similarly beennormalized to the same reference device.

Via normalization, some embodiments may account for the wide variety ofcamera intrinsics potentially used by XR devices attempting remote orcloud-based localization. Some embodiments may account for the fact thatmany XR devices may be configured to capture two-dimensional images,whereas a benchmark device may be configured to capturethree-dimensional images.

In some embodiments, normalization may be achieved by changing valuesfor a parameter of interest for pixels in an image, to equal orapproximate the values expected if the image were captured by thebenchmark device. For example, gamma correction may be performed tomodify brightness values for one or more pixels of an image, to equal orapproximate the brightness values expected if the image were captured bythe benchmark device. In some embodiments, normalization may be achievedby mapping values for a parameter of interest for pixels in an image ofone size captured by the XR device to pixels in of another size capturedby the benchmark device. For example, if the XR device captures imageshaving half the number of pixels as are included in images captured bythe benchmark device, then the values for the pixels captured by the XRdevice may be interpolated to create an image having the values expectedif the image were captured by the benchmark device.

As an example of another normalization technique, multiple images mightbe combined to form a single normalized image. In a scenario in whichthe images provided a portable device have a smaller angular field ofview than a reference image, data from multiple images may be fused toproduce an image with a larger angular field of view. Conversely, ratherthan performing normalization on device 7150, information about theintrinsics of the device capturing the images might be collected andpassed to PW cloud service 7140 for normalization processing. Withprocessing in the cloud, characteristics of the images to which theimages captured by device 7150 is to be compared alternatively oradditionally may be modified, such as to reduce pixel density ordecrease angular field of view, so as to enable a more reliablecomparison of the images for which information stored in PW cloudservice 7140 was generated and the images captured by device 7150.

Other suitable technique(s) may be used to normalize values from oneimage type to another, and the same technique need not be used tonormalize the values for all parameters, or for all pixels.

At the completion of act 7230, representative process 7200 proceeds toact 7240, wherein feature descriptors for the image are generated.Feature descriptors may be generated in any of numerous ways, such as inthe manner described above in relation to act 6206 of the process shownin FIG. 62 .

In some embodiments, as described above, feature descriptors may begenerated using one or more artificial neural networks trained with alabeled data set of images of features that represent persistentlocations in the physical world that can be reliably detected each timea device images that region of the physical world. In some embodiments,a similar training process may be used to create an artificial neuralnetwork for generating feature descriptors in an XR system that supportsmultiple device types, but the training set of images may include imagescaptured with a device of the same type as 7150, or otherwise with thesame camera intrinsics. For example, a portion of the images in thetraining set may be captured with a camera having characteristics of thereference camera and another portion having characteristics of thecamera of the device for which the neural network will be used toprocess images.

In some embodiments, the number of feature descriptors generated for agiven image may depend, at least in part, upon the camera intrinsics ofthe XR device that captured the image. For example, the imageresolution, focal length, angular field of view and/or other cameraintrinsics of an XR device may influence the number of featuredescriptors generated for a given image captured by the XR device.Localization is, on some level at least, a probabilistic procedure, andwith certain cameras it may be necessary to increase the number offeature descriptors generated from images it captures to accomplishsuccessful localization. Of course, the number of feature descriptorsgenerated for the images captured by any specific XR devices may bedetermined in any suitable fashion, as the invention is not limited inthis respect.

Regardless of the number of feature descriptors generated, each featuremay be posed, as described above, so as to indicate the location of thefeature in a local coordinate system. The pose may be based onperception data provided by native AR platform 7160.

Representative process 7200 then proceeds to act 7250, wherein thefeature descriptors generated in the act 7240 are transmitted to aremote localization service. Transmission may be accomplished in any ofnumerous ways. The feature descriptors may be transmitted in a protocoland in conjunction with information as described above for a remotelocalization process. For example, the feature descriptors may be sentin connection with geographic data, such as GPS data or a wirelessfingerprint, enabling the localization process to be performed asdescribed above. As described above in relation to the process depictedin FIG. 62 , in some embodiments, feature descriptors may be stored in abuffer prior to being transmitted to a localization service, and thefrequency at which buffer contents are transmitted, and/or the amount ofinformation (e.g., number of feature descriptors) may be determineddynamically in response to whether localization is successful.Representative process 7200 then completes.

FIG. 73 depicts a representative process 7300 whereby a remotelocalization service (e.g., cloud-based localization service 7130, FIG.71 ) may provide location information to an XR device (e.g., XR device7150). At the start of representative process 7300, an XR device and itstype are identified in act 7310. This may be performed in any ofnumerous ways. For example, in some embodiments, authentication/identityservice 7135 (FIG. 71 ) of a remote localization service may identifythe XR device and its type based on information provided by the XRdevice. This information may be used at the remote localization servicefor authorizing actions or other purposes, such as to tailorlocalization processing based on the type of device requestinglocalization services.

The process then proceeds to act 7320, wherein feature descriptors arereceived from the XR device. For example, feature descriptors may betransmitted by the XR device in the manner described above in relationto representative process 7200 (FIG. 72 ).

In act 7330, the remote or cloud-based localization service performslocalization. This may be performed, for example, using the techniquesdescribed above in relation to FIG. 62 . Any of the functions describedin connection with localization may be performed. For example,information, such as session information or localization history for thedevice, may be stored, for example.

In some embodiments, the localization process may be varied based on thetype of device. For example, wearable devices having stereoscopiccameras may generate 3D pose information in connection with the set offeatures sent for localization. For such devices, localization mayentail matching a point cloud of features in 3D. To support thisoperation, canonical maps may represent persistent points with 3Dclusters of features. However, in some embodiments, accuracy of matchingfeatures extracted from images taken with a monocular camera to a 3D setof features may be poor. Accuracy may be improved, for example, byprojecting the 3D cluster of features, such as might be stored in acanonical map, into a plane and performing a 2D mapping within thatplane.

Representative process 7300 then proceeds to act 7340, where the resultsof the localization are provided to the device. The results may beprovided as described above, as a transform from a coordinate framedescribing the locations of the features sent for localization to one ormore coordinate frames associated with a canonical map or other sharedmap maintained by the localization service.

Representative Process 7300 then Completes.

Once the process ends with the device 7150 having a transformationbetween its local coordinate frame and a coordinate frame used by the XRsystem 7120 to specify the position of virtual content, device 7150 mayrender content in the specified locations. This rendering may be done bythe native AR framework 7160. In embodiments in which native ARframework 7160 uses a format for specifying virtual content differentthan other components of system 7120, one or more content translatorsmay be provided. Such content translators may be within remote services7130, and an appropriate translator may be selected based on deviceinformation provided to remote services 7130 in connection with alocalization request.

In this way, a device, such as a smartphone, not designed to work withXR system 7120 may work with that system. It should be appreciated that,in addition to rendering virtual content as described above, such adevice may be programmed or otherwise configured to perform any of thefunctions described herein of a portable device as described herein.

Geo-Location Enhanced Map Ranking and Merging

Geo-location metadata associated with location information from portabledevices and associated with canonical maps, or sub-portions of canonicalmaps such as tiles, may similarly make map merge processing fasterand/or more efficient. As described above, a set of canonical maps ofthe environment in which multiple XR devices operate may provide anenhanced XR experience to multiple users using different computingdevices (such as portable devices, including smart phones and XRdevices) by enabling their local representations of the world (e.g., inthe form of tracking maps) to be transformed to the same coordinateframe. By localizing to the same frame of reference, all of the devicesmay present, to their users, virtual content in the same locationrelative to the physical world, creating a more realistic and immersiveshared user experience.

The canonical maps may be created by incrementally merging tracking mapsreceived from the users' devices to create a virtual representation ofthe world. In some embodiments, users' devices may send their trackingmaps to a cloud-based service to merge with map(s) of the environmentpreviously stored in the cloud-based service. The map merge component,such as map merge component 7718 (FIG. 77 ) of the cloud service, mayattempt to identify a portion of each new tracking map that representsthe same region of the physical world as a portion of an existingcanonical map. This identification may be made in steps, with an initialstep involving finding likely regions of overlap between the trackingmap and a canonical map by matching location metadata associated withregions of the already stored canonical maps to similar locationmetadata associated with portions of the tracking map. Alternatively, oradditionally, descriptors computed for key frames in the tracking mapmay be matched to similar descriptors associated with portions of thecanonical map. These likely regions of overlap serve as candidates forfurther processing.

These candidate regions of overlap may be further processed to identifyfeature points in the tracking map with corresponding feature points inthe canonical map. Corresponding features may be identified based oncharacteristics of the features. For example, corresponding features maybe identified based on similar descriptors, such as DSF descriptorsdescribed above, being assigned to features in the tracking map and thecanonical map.

Further steps in the map merge process may entail determining atransformation between the sets of corresponding features that providesa suitably low error between the positions of the transformed featuresin a first set of features derived from the tracking map and a secondset of features derived from the canonical map. One or more errormetrics may be applied to compare error to a threshold. For example, thenumber or percentage of feature points in the tracking map that, aftertransformation, are within a threshold distance of their correspondingfeature point in the canonical map may be used as an error metric.Alternatively, or additionally, error may be measured based on distancebetween transformed feature points from the tracking map and theircorresponding features in the canonical map. As a specific example, anerror measure may be the root mean squared distance for the set ofcorresponding feature points.

The inventors have appreciated, however, that determining atransformation between the sets of corresponding features may becomputationally costly, especially when large canonical maps areconsidered. Moreover, map merge may entail identifying multiple sets ofthe tracking map that correspond, with similar transformations, tofeatures of the canonical map, such that this process may be repeatedmultiple times for a successful map merge. Thus, map merging algorithmsthat rely on such transformations are also computationally costly. Insome embodiments, map merging algorithms may be performed oversub-portions of canonical maps, rather than over entire canonical maps.This means that the transformation is also performed over a sub-portionof a canonical map, thus utilizing substantially fewer computationalresources.

As with localization algorithms, map merging algorithms may be made moreefficient by relying on location metadata obtained from a portabledevice. An example of a portable device generating a tracking mapcontaining location metadata (e.g., Wi-Fi fingerprints, geo-location,GPS data, etc.) was described above in connection with FIG. 75 . In thatexample, a Wi-Fi fingerprint, as described above, is shown inconjunction with geo-location metadata. Some devices may collect both ofthese types of metadata, in addition to possibly other types of locationmetadata. However, in some embodiments, a single device may collecteither Wi-Fi fingerprints or other geo-location data. These and othertypes of location metadata may be used to initially identify candidatesub-portions of a canonical map to be input to a map merge process.

Further efficiencies may be achieved by performing map merge algorithmsover sub-portions of canonical maps, rather than over entire canonicalmaps, thus utilizing less computational power. FIG. 79 is a flowchartillustrating an example of a map merge algorithm that may be performedover sub-portions of canonical maps. Any suitable computing device mayexecute map merge algorithm 7900. In some embodiments, a map mergeportion 810 (see FIG. 26 ) or map merge component 7718 (FIG. 77 ) mayexecute map merge algorithm 7900. Map merge algorithm 7900 may begin atact 7902, in which the computing device receives location metadataassociated with a tracking map generated by a portable device.

The received location metadata may be associated with one or moreparticular tiles or particular persistent locations (such as apersistent coordinate frame or a persistent pose) of a tracking map or,alternatively or additionally, may refer to the entirety of a trackingmap. The location metadata received from the portable device may includea wireless fingerprint, geo-location data (such as GPS data) or othertypes of location metadata, depending on the portable device that sendsthe data.

In some embodiments, location metadata of a canonical map may beexpressed in terms of GPS data and location metadata received from aportable device may be expressed in terms of Wi-Fi fingerprints, meaningthat the location metadata may not be directly compared to one anotherabsent data conversion. In some embodiments, the Wi-Fi fingerprintsreceived from a portable device may be converted to GPS data, thusrendering the location metadata received from the portable devicecompatible to the location metadata of the canonical map. The conversionmay be performed using GOGGLE geo-location APIs or otherpublicly-accessible APIs. Moreover, as described above, when a cloudprocess associates with a tracking map location metadata in a convertedform, it may return that converted location metadata to the device, suchthat, in subsequent operations, the device may send location metadata ina format for which conversion is not required.

At act 7904, the computing device determines whether there is at leastone sub-portion in the tracking map that likely corresponds to asub-portion in the canonical map that is a candidate sub-portion forfurther processing. In some embodiments, likely correspondingsub-portions may be identified based on the location metadata receivedfrom a portable device and location metadata associated with thecanonical map. These comparisons of location metadata may be performedas described above in connection with comparing location metadata inconnection with localization processing. Comparisons, for example, maybe based on geo-hash difference or Jaccard similarity, depending on thetype of location metadata.

If the computing device determines that there are no likelycorresponding sub-portions, map merge algorithm 7900 may end, meaningthat the step of merging the canonical map with the tracking map isskipped. The processing skipped may include computationally intensivefeature-based comparisons to determine whether likely correspondingsub-portions do correspond. Thus, identifying that there are nocandidate sub-portions for further processing may reduce the amount ofcomputational resources expended on map merge.

In some embodiments, when no corresponding sub-portions are found, thetracking map may be treated as depicting a portion of the 3D environmentnot represented in any canonical map maintained by a cloud service. Inthat scenario, the tracking map be stored as a new canonical map in auniverse of canonical maps, or may be otherwise processed as describedherein for a tracking map that does not sufficiently overlap an existingcanonical map.

If the computing device determines that there are sufficient candidatesub-portions, map merge algorithm 7900 proceeds to act 7906, in which acandidate sub-portion of the canonical map is selected for furtherprocessing based on the location metadata comparison. In thisembodiment, the selected sub-portion of the canonical map is smallerthan the entire canonical map.

The selection of act 7906 may be performed based on location metadataand/or descriptors or as otherwise described herein. For example, theselection may entail identifying a particular location in the canonicalmap, such as a PCF, with location metadata that differs from locationmetadata associated with a persistent pose in the tracking map by lessthan a threshold amount. The selected region of the canonical map may bewithin a certain range of this location. In some embodiments, the rangemay be determined based on the uncertainty associated with the locationmetadata. For example, the range may be the radius around a wirelessnetwork access point over which the access point may transmit a beaconwith an RSSI above a threshold. In other embodiments, the range may beset to a certain predefined value, such as 10 meters, 20 meters, 30meters or 50 meters. In yet other embodiments, a canonical map may besub-divided in tiles (as shown in FIG. 69 ), and selecting a sub-portionof a canonical map may involve selecting one or more tiles of thecanonical map, such as the tile containing the particular location, plussome or all of the neighboring tiles.

At act 7908, the computing device merges the tracking map with theselected sub-portion of the canonical map. The merging may involvecomputing a transformation that aligns sets of features of the trackingmap with corresponding sets of features in the canonical map, withsufficiently low error. In some embodiments, merge processing may bebased on one set of features in the tracking map, such as associatedwith a keyframe, and a corresponding set of features in the canonicalmap. In other embodiments, however, maps may be merged only if there areconsistent transformations between multiple corresponding sets offeatures, so as to ensure the accuracy of the resulting canonical maps.Other accuracy criteria may alternatively or additionally be applied asa precondition to merging. For example, the transformations that resultin correspondence between multiple sets of features may be used formerging only if the transformation preserves the orientation of thetracking map with respect to the direction of gravity.

When the criteria for a merge are met, merging may result in a mergedsub-portion that includes replacement information for the sub-portion ofthe canonical map selected at act 7906. That merged sub-portion may becomputed for map merge processing as described elsewhere herein, such asby aggregating information from both maps to be merged, with or withoutomitting some of the information. In some scenarios, the mergedsub-portion may include location information from portions of thetracking map extending beyond the selected sub-portion of the canonicalmap. That location information may be used to extend the canonical map,as in a conventional map merge as described above.

At act 7910, the merged map sub-portion obtained at act 7908 may beintegrated with the canonical map, updating and or extendingsub-portions of the canonical map. The computing device may store thecanonical map obtained at act 7910 in a non-volatile memory. Thecanonical map obtained in this manner may subsequently be used in VR orAR environments in accordance with any of the embodiments describedherein.

Further Considerations

FIG. 60 shows a diagrammatic representation of a machine in theexemplary form of a computer system 1900 within which a set ofinstructions, for causing the machine to perform any one or more of themethodologies discussed herein, may be executed, according to someembodiments. In alternative embodiments, the machine operates as astandalone device or may be connected (e.g., networked) to othermachines. Further, while only a single machine is illustrated, the term“machine” shall also be taken to include any collection of machines thatindividually or jointly execute a set (or multiple sets) of instructionsto perform any one or more of the methodologies discussed herein.

The exemplary computer system 1900 includes a processor 1902 (e.g., acentral processing unit (CPU), a graphics processing unit (GPU) orboth), a main memory 1904 (e.g., read only memory (ROM), flash memory,dynamic random-access memory (DRAM) such as synchronous DRAM (SDRAM) orRambus DRAM (RDRAM), etc.), and a static memory 1906 (e.g., flashmemory, static random-access memory (SRAM), etc.), which communicatewith each other via a bus 1908.

The computer system 1900 may further include a disk drive unit 1916, anda network interface device 1920.

The disk drive unit 1916 includes a machine-readable medium 1922 onwhich is stored one or more sets of instructions 1924 (e.g., software)embodying any one or more of the methodologies or functions describedherein. The software may also reside, completely or at least partially,within the main memory 1904 and/or within the processor 1902 duringexecution thereof by the computer system 1900, the main memory 1904 andthe processor 1902 also constituting machine-readable media.

The software may further be transmitted or received over a network 18via the network interface device 1920.

The computer system 1900 includes a driver chip 1950 that is used todrive projectors to generate light. The driver chip 1950 includes itsown data store 1960 and its own processor 1962.

While the machine-readable medium 1922 is shown in an exemplaryembodiment to be a single medium, the term “machine-readable medium”should be taken to include a single medium or multiple medium (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“machine-readable medium” shall also be taken to include any medium thatis capable of storing, encoding, or carrying a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies of the present invention. The term“machine-readable medium” shall accordingly be taken to include, but notbe limited to, solid-state memories, optical and magnetic media, andcarrier wave signals.

Having thus described several aspects of some embodiments, it is to beappreciated that various alterations, modifications, and improvementswill readily occur to those skilled in the art.

As one example, embodiments are described in connection with anaugmented (AR) environment. It should be appreciated that some or all ofthe techniques described herein may be applied in an MR environment ormore generally in other XR environments, and in VR environments.

As another example, embodiments are described in connection withdevices, such as wearable devices. It should be appreciated that some orall of the techniques described herein may be implemented via networks(such as cloud), discrete applications, and/or any suitable combinationsof devices, networks, and discrete applications.

Further, FIG. 29 provides examples of criteria that may be used tofilter candidate maps to yield a set of high-ranking maps. Othercriteria may be used instead of or in addition to the describedcriteria. For example, if multiple candidate maps have similar values ofa metric used for filtering out less desirable maps, characteristics ofthe candidate maps may be used to determine which maps are retained ascandidate maps or filtered out. For example, larger or more densecandidate maps may be prioritized over smaller candidate maps.

It shall be noted that any obvious alterations, modifications, andimprovements are contemplated and intended to be part of thisdisclosure, and are intended to be within the spirit and scope of thedisclosure. Further, though advantages of the present disclosure areindicated, it should be appreciated that not every embodiment of thedisclosure will include every described advantage. Some embodiments maynot implement any features described as advantageous herein and in someinstances. Accordingly, the foregoing description and drawings are byway of example only.

The above-described embodiments of the present disclosure can beimplemented in any of numerous ways. For example, the embodiments may beimplemented using hardware, software or a combination thereof. Whenimplemented in software, the software code can be executed on anysuitable processor or collection of processors, whether provided in asingle computer or distributed among multiple computers. Such processorsmay be implemented as integrated circuits, with one or more processorsin an integrated circuit component, including commercially availableintegrated circuit components known in the art by names such as CPUchips, GPU chips, microprocessor, microcontroller, or co-processor. Insome embodiments, a processor may be implemented in custom circuitry,such as an ASIC, or semicustom circuitry resulting from configuring aprogrammable logic device. As yet a further alternative, a processor maybe a portion of a larger circuit or semiconductor device, whethercommercially available, semi-custom or custom. As a specific example,some commercially available microprocessors have multiple cores suchthat one or a subset of those cores may constitute a processor. Though,a processor may be implemented using circuitry in any suitable format.

Further, it should be appreciated that a computer may be embodied in anyof a number of forms, such as a rack-mounted computer, a desktopcomputer, a laptop computer, or a tablet computer. Additionally, acomputer may be embedded in a device not generally regarded as acomputer but with suitable processing capabilities, including a PersonalDigital Assistant (PDA), a smart phone or any other suitable portable orfixed electronic device.

Also, a computer may have one or more input and output devices. Thesedevices can be used, among other things, to present a user interface.Examples of output devices that can be used to provide a user interfaceinclude printers or display screens for visual presentation of outputand speakers or other sound generating devices for audible presentationof output. Examples of input devices that can be used for a userinterface include keyboards, and pointing devices, such as mice, touchpads, and digitizing tablets. As another example, a computer may receiveinput information through speech recognition or in other audible format.In the embodiment illustrated, the input/output devices are illustratedas physically separate from the computing device. In some embodiments,however, the input and/or output devices may be physically integratedinto the same unit as the processor or other elements of the computingdevice. For example, a keyboard might be implemented as a soft keyboardon a touch screen. In some embodiments, the input/output devices may beentirely disconnected from the computing device, and functionallyintegrated through a wireless connection.

Such computers may be interconnected by one or more networks in anysuitable form, including as a local area network or a wide area network,such as an enterprise network or the Internet. Such networks may bebased on any suitable technology and may operate according to anysuitable protocol and may include wireless networks, wired networks orfiber optic networks.

Also, the various methods or processes outlined herein may be coded assoftware that is executable on one or more processors that employ anyone of a variety of operating systems or platforms. Additionally, suchsoftware may be written using any of a number of suitable programminglanguages and/or programming or scripting tools, and also may becompiled as executable machine language code or intermediate code thatis executed on a framework or virtual machine.

In this respect, the disclosure may be embodied as a computer readablestorage medium (or multiple computer readable media) (e.g., a computermemory, one or more floppy discs, compact discs (CD), optical discs,digital video disks (DVD), magnetic tapes, flash memories, circuitconfigurations in Field Programmable Gate Arrays or other semiconductordevices, or other tangible computer storage medium) encoded with one ormore programs that, when executed on one or more computers or otherprocessors, perform methods that implement the various embodiments ofthe disclosure discussed above. As is apparent from the foregoingexamples, a computer readable storage medium may retain information fora sufficient time to provide computer-executable instructions in anon-transitory form. Such a computer readable storage medium or mediacan be transportable, such that the program or programs stored thereoncan be loaded onto one or more different computers or other processorsto implement various aspects of the present disclosure as discussedabove. As used herein, the term “computer-readable storage medium”encompasses only a computer-readable medium that can be considered to bea manufacture (i.e., article of manufacture) or a machine. In someembodiments, the disclosure may be embodied as a computer readablemedium other than a computer-readable storage medium, such as apropagating signal.

The terms “program” or “software” are used herein in a generic sense torefer to any type of computer code or set of computer-executableinstructions that can be employed to program a computer or otherprocessor to implement various aspects of the present disclosure asdiscussed above. Additionally, it should be appreciated that accordingto one aspect of this embodiment, one or more computer programs thatwhen executed perform methods of the present disclosure need not resideon a single computer or processor, but may be distributed in a modularfashion amongst a number of different computers or processors toimplement various aspects of the present disclosure.

Computer-executable instructions may be in many forms, such as programmodules, executed by one or more computers or other devices. Generally,program modules include routines, programs, objects, components, datastructures, etc. that perform particular tasks or implement particularabstract data types. Typically, the functionality of the program modulesmay be combined or distributed as desired in various embodiments.

Also, data structures may be stored in computer-readable media in anysuitable form. For simplicity of illustration, data structures may beshown to have fields that are related through location in the datastructure. Such relationships may likewise be achieved by assigningstorage for the fields with locations in a computer-readable medium thatconveys relationship between the fields. However, any suitable mechanismmay be used to establish a relationship between information in fields ofa data structure, including through the use of pointers, tags or othermechanisms that establish relationship between data elements.

Various aspects of the present disclosure may be used alone, incombination, or in a variety of arrangements not specifically discussedin the embodiments described in the foregoing and is therefore notlimited in its application to the details and arrangement of componentsset forth in the foregoing description or illustrated in the drawings.For example, aspects described in one embodiment may be combined in anymanner with aspects described in other embodiments.

Also, the disclosure may be embodied as a method, of which an examplehas been provided. The acts performed as part of the method may beordered in any suitable way. Accordingly, embodiments may be constructedin which acts are performed in an order different than illustrated,which may include performing some acts simultaneously, even though shownas sequential acts in illustrative embodiments.

Use of ordinal terms such as “first,” “second,” “third,” etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having a same name (but for use of the ordinalterm) to distinguish the claim elements.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

1. A portable electronic system, comprising: a processor; a sparse mapthat is constructed by a portable electronic system and stored in anon-transitory computer readable medium, wherein the sparse map furthercomprises location data of one or more features in a physicalenvironment; memory storing thereupon a sequence of instructions which,when executed by the processor, causes the processor to perform a set ofacts, the set of acts comprising: receiving, at the portable electronicsystem, a set of one or more canonical maps; determining, at theportable electronic system, the sparse map based at least in part uponone or more anchors according to the physical environment; localizingthe sparse map to at least one canonical map in the set of one or morecanonical maps; and creating a new canonical map at least by mergingsparse map data of the sparse map into the at least one canonical map.2. The portable electronic system of claim 1, receiving the set of oneor more canonical maps comprising: identifying a universe of canonicalmaps having a plurality of canonical maps; determining one or morefiltering schemes from a plurality of filtering schemes based at leastin part upon a characteristic of the universe of canonical maps; andfiltering the universe of canonical maps at least by applying the one ormore filtering schemes to the universe of canonical maps.
 3. Theportable electronic system of claim 2, receiving the set of one or morecanonical maps further comprising: identifying a local feature stringfrom the sparse map; identifying a global feature string from a reducedset of canonical maps comprising the at least one canonical map; anddetermining whether the local feature string matches the global featurestring.
 4. The portable electronic system of claim 3, wherein the globalfeature string is locally generated by the portable electronic system.5. The portable electronic system of claim 2, determining the one ormore filtering schemes comprising: upon a determination that a firstfiltering scheme is to be applied to the universe of canonical maps,identifying system location data or information pertaining to one ormore prior maps to which the portable electronic system has beenlocalized; determining one or more neighboring canonical maps based atleast by filtering the universe of canonical maps with the systemlocation data of the portable electronic system, wherein a neighboringcanonical map includes neighboring canonical map location data thatencompasses or is within a close proximity of the system location data;and identifying the one or more neighboring canonical maps into areduced universe of canonical maps.
 6. The portable electronic system ofclaim 5, determining the one or more filtering schemes comprising: upona determination that a second filtering scheme is to be applied to theuniverse of canonical maps or to the reduced universe of canonical maps,identifying wireless fingerprinting data for the portable electronicsystem, wherein the wireless fingerprinting data is determined based atleast in part upon at least one of a basic service set identifier(BSSID), a Wi-Fi signal, a global positioning system (GPS) signal, or areceived signal strength indicator (RSSI) signal; determining a regionin the physical environment based at least in part upon the wirelessfingerprinting data for the portable electronic system; and filteringthe universe of canonical maps or the reduced universe of canonical mapsinto a first subset of canonical maps based at least in part upon theregion determined from the physical environment.
 7. The portableelectronic system of claim 6, determining the one or more filteringschemes comprising: upon a determination that a third filtering schemeis to be applied to the universe of canonical maps, the reduced universeof canonical maps, or the first subset of canonical maps, determiningone or more keyframes, one or more two-dimensional (2D) orthree-dimensional (3D) features, or one or more global feature strings,wherein a 2D or 3D feature comprises a localized pose and a set of2D-to-3D correspondences; and determining a second subset of one or morecanonical maps the universe of canonical maps, the reduced universe ofcanonical maps, or the first subset of canonical maps based at least inpart upon the one or more keyframes, the one or more two-dimensional(2D) or three-dimensional (3D) features, or the one or more globalfeature strings.
 8. The portable electronic system of claim 1,localizing the sparse map to the at least one canonical map comprising:identifying the sparse map and a universe of canonical maps having aplurality of canonical maps; and splitting the sparse map into aplurality of connected component, wherein a connected component of theplurality of connected components includes one or more three-dimensional(3D) features that are connected and located within a predetermineddistance.
 9. The portable electronic system of claim 8, localizing thesparse map to the at least one canonical map further comprising:identifying a predetermined threshold for the plurality of connectedcomponents; determining one or more connected components from theplurality of connected components that satisfy a constraint pertainingto the predetermined threshold; merging the one or more connectedcomponents into one or more canonical maps; and merging the one or morecanonical maps into a merged canonical map.
 10. The portable electronicsystem of claim 9, localizing the sparse map to the at least onecanonical map further comprising: determining one or more remainingconnected components from the plurality of connected components, whereina remaining connected component does not satisfy the constraintpertaining to the predetermined threshold; and promoting the one or moreremaining connected components into a separate canonical map.
 11. Theportable electronic system of claim 10, localizing the sparse map to theat least one canonical map further comprising: identifying one or moresparse map poses or one or more sparse map persistent coordinate frames(PCFs) pertaining to the sparse map; identifying one or more canonicalmap poses or one or more canonical map persistent coordinate frames(PCFs) pertaining to the merged canonical map; and performing at leastone of a first merger or a second merger.
 12. The portable electronicsystem of claim 11, wherein the first merger merges one or more sparsemap poses pertaining to the sparse map into the one or more canonicalmap poses pertaining to the merged canonical map; and the second mergermerges one or more sparse map PCFs pertaining to the sparse map into theone or more canonical map PCFs pertaining to the merged canonical map.13. The portable electronic system of claim 11, localizing the sparsemap to the at least one canonical map further comprising fusing aplurality of map points in the merged canonical map based at least inpart upon the first merger or the second merger.
 14. The portableelectronic system of claim 13, localizing the sparse map to the at leastone canonical map further comprising pruning at least onethree-dimensional (3D) feature from the merged canonical map or from themerged canonical map.
 15. A method, comprising: receiving, at theportable electronic system, a set of one or more canonical maps;determining, at the portable electronic system, the sparse map based atleast in part upon one or more anchors according to the physicalenvironment; localizing the sparse map to at least one canonical map inthe set of one or more canonical maps; and creating a new canonical mapat least by merging sparse map data of the sparse map into the at leastone canonical map.
 16. The method of claim 15, receiving the set of oneor more canonical maps comprising: identifying a universe of canonicalmaps having a plurality of canonical maps; determining one or morefiltering schemes from a plurality of filtering schemes based at leastin part upon a characteristic of the universe of canonical maps;filtering the universe of canonical maps at least by applying the one ormore filtering schemes to the universe of canonical maps; identifying alocal feature string from the sparse map; identifying a global featurestring from a reduced set of canonical maps comprising the at least onecanonical map; and determining whether the local feature string matchesthe global feature string, wherein the global feature string is locallygenerated by the portable electronic system.
 17. The method of claim 16,receiving the set of one or more canonical maps comprising: upon a firstdetermination that a first filtering scheme is to be applied to theuniverse of canonical maps, identifying system location data orinformation pertaining to one or more prior maps to which the portableelectronic system has been localized; determining one or moreneighboring canonical maps based at least by filtering the universe ofcanonical maps with the system location data of the portable electronicsystem, wherein a neighboring canonical map includes neighboringcanonical map location data that encompasses or is within a closeproximity of the system location data; and identifying the one or moreneighboring canonical maps into a reduced universe of canonical maps;upon a determination that a second filtering scheme is to be applied tothe universe of canonical maps or to the reduced universe of canonicalmaps, identifying wireless fingerprinting data for the portableelectronic system, wherein the wireless fingerprinting data isdetermined based at least in part upon at least one of a basic serviceset identifier (BSSID), a Wi-Fi signal, a global positioning system(GPS) signal, or a received signal strength indicator (RSSI) signal;determining a region in the physical environment based at least in partupon the wireless fingerprinting data for the portable electronicsystem; and filtering the universe of canonical maps or the reduceduniverse of canonical maps into a first subset of canonical maps basedat least in part upon the region determined from the physicalenvironment; or upon a determination that a third filtering scheme is tobe applied to the universe of canonical maps, the reduced universe ofcanonical maps, or the first subset of canonical maps, determining oneor more keyframes, one or more two-dimensional (2D) or three-dimensional(3D) features, or one or more global feature strings, wherein a 2D or 3Dfeature comprises a localized pose and a set of 2D-to-3Dcorrespondences; and determining a second subset of one or morecanonical maps the universe of canonical maps, the reduced universe ofcanonical maps, or the first subset of canonical maps based at least inpart upon the one or more keyframes, the one or more two-dimensional(2D) or three-dimensional (3D) features, or the one or more globalfeature strings.
 18. A computer program product comprising anon-transitory computer readable storage medium having stored thereupona sequence of instructions which, when executed by a processor, causesthe processor to perform a set of acts for rendering virtual content forextended-reality, the set of acts comprising: receiving, at the portableelectronic system, a set of one or more canonical maps; determining, atthe portable electronic system, the sparse map based at least in partupon one or more anchors according to the physical environment;localizing the sparse map to at least one canonical map in the set ofone or more canonical maps; and creating a new canonical map at least bymerging sparse map data of the sparse map into the at least onecanonical map.
 19. The computer program product of claim 18, furthercomprising the sequence of instructions for receiving the set of one ormore canonical maps which, when executed by the processor, furthercauses the processor to perform the set of acts, the set of acts furthercomprising: identifying a universe of canonical maps having a pluralityof canonical maps; determining one or more filtering schemes from aplurality of filtering schemes based at least in part upon acharacteristic of the universe of canonical maps; filtering the universeof canonical maps at least by applying the one or more filtering schemesto the universe of canonical maps; identifying a local feature stringfrom the sparse map; identifying a global feature string from a reducedset of canonical maps comprising the at least one canonical map; anddetermining whether the local feature string matches the global featurestring, wherein the global feature string is locally generated by theportable electronic system.
 20. The computer program product of claim18, further comprising the sequence of instructions for localizing thesparse map to the at least one canonical map which, when executed by theprocessor, further causes the processor to perform the set of acts, theset of acts further comprising: identifying the sparse map and auniverse of canonical maps having a plurality of canonical maps;splitting the sparse map into a plurality of connected component,wherein a connected component of the plurality of connected componentsincludes one or more three-dimensional (3D) features that are connectedand located within a predetermined distance; identifying a predeterminedthreshold for the plurality of connected components; determining one ormore connected components from the plurality of connected componentsthat satisfy a constraint pertaining to the predetermined threshold;merging the one or more connected components into one or more canonicalmaps; merging the one or more canonical maps into a merged canonicalmap; determining one or more remaining connected components from theplurality of connected components, wherein a remaining connectedcomponent does not satisfy the constraint pertaining to thepredetermined threshold; promoting the one or more remaining connectedcomponents into a separate canonical map; identifying one or more sparsemap poses or one or more sparse map persistent coordinate frames (PCFs)pertaining to the sparse map; identifying one or more canonical mapposes or one or more canonical map persistent coordinate frames (PCFs)pertaining to the merged canonical map; performing at least one of afirst merger or a second merger, wherein the first merger merges one ormore sparse map poses pertaining to the sparse map into the one or morecanonical map poses pertaining to the merged canonical map; and thesecond merger merges one or more sparse map PCFs pertaining to thesparse map into the one or more canonical map PCFs pertaining to themerged canonical map; and fusing a plurality of map points in the mergedcanonical map based at least in part upon the first merger or the secondmerger.